Charging system and charging method, and power adapter

ABSTRACT

The present disclosure discloses a charging system, a charging method and a power adapter. The system includes a battery, a first rectifier, a switch unit, a transformer, a compositing unit, a sampling unit, and a control unit. The control unit outputs a control signal to the switch unit, and adjusts a duty ratio of the control signal according to a voltage sampling value and/or a current sampling value obtained by primary sampling of the sampling unit, such that a second alternating current outputted by the compositing unit meets a charging requirement. The second alternating current is applied to the battery.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims a priority to Chinese PatentApplication Serial No. 201610599782.4, filed on Jul. 26, 2016, theentire contents of which are incorporated herein by reference

TECHNICAL FIELD

The present disclosure generally relates to a terminal technical field,and more particularly, to a charging system, a charging method, and apower adapter.

BACKGROUND

Nowadays, mobile terminals such as smart phones are favored by more andmore consumers. However, the mobile terminal consumes large powerenergy, and needs to be charged frequently.

Typically, the mobile terminal is charged by a power adapter. The poweradapter generally includes a primary rectifier circuit, a primary filtercircuit, a transformer, a secondary rectifier circuit, a secondaryfilter circuit and a control circuit, such that the power adapterconverts the input alternating current of 220V into a stable and lowvoltage direct current (for example, 5V) suitable for requirements ofthe mobile terminal, and provides the direct current to a powermanagement device and a battery of the mobile terminal, therebyrealizing charging the mobile terminal.

However, with the increasing of the power of the power adapter, forexample, from 5 W to larger power such as 10 W, 15 W, 25 W, it needsmore electronic elements capable of bearing large power and realizingbetter control for adaptation, which not only increases a size of thepower adapter, but also increases a production cost and manufacturedifficulty of the power adapter.

SUMMARY

Embodiments of the present disclosure provide a charging system. Thecharging system includes a power adapter and a terminal. The poweradapter includes: a first rectifier, configured to rectify a firstalternating current and output a first voltage with a first ripplewaveform; a switch unit, configured to modulate the first voltageaccording to a control signal and output a modulated first voltage; atransformer, configured to output a plurality of voltages with ripplewaveforms according to the modulated first voltage; a compositing unit,configured to composite the plurality of voltages to output a secondalternating current, in which, for each cycle of the second alternatingcurrent, a peak voltage of a positive half is greater than an absolutevalue of a valley voltage of a negative half; a sampling unit,configured to sample voltage and/or current at a primary winding of thetransformer to obtain a voltage sampling value and/or a current samplingvalue; and a control unit, coupled to the sampling unit and the switchunit respectively, and configured to output the control signal to theswitch unit, to adjust a duty ratio of the control signal according tothe current sampling value and/or the voltage sampling value, such thatthe second alternating current meets a charging requirement of theterminal when the power adapter is coupled to the terminal. The terminalincludes a battery, the second alternating current is configured to beintroduced into a terminal to charge a battery in the terminal when thepower adapter is coupled to the terminal.

Embodiments of the present disclosure provide a power adapter. The poweradapter includes: a first rectifier, configured to rectify a firstalternating current and output a first voltage with a first ripplewaveform; a switch unit, configured to modulate the first voltageaccording to a control signal and output a modulated first voltage; atransformer, configured to output a plurality of voltages with ripplewaveforms according to the modulated first voltage; a compositing unit,configured to composite the plurality of voltages to output a secondalternating current, in which, for each cycle of the second alternatingcurrent, a peak voltage of a positive half is greater than an absolutevalue of a valley voltage of a negative half, and the second alternatingcurrent is configured to be introduced into a terminal to charge abattery in the terminal when the power adapter is coupled to theterminal; a sampling unit, configured to sample voltage and/or currentat a primary winding of the transformer to obtain a voltage samplingvalue and/or a current sampling value; a control unit, coupled to thesampling unit and the switch unit respectively, and configured to outputthe control signal to the switch unit, and to adjust a duty ratio of thecontrol signal according to the current sampling value and/or thevoltage sampling value, such that the second alternating current meets acharging requirement of the terminal when the power adapter is coupledto the terminal.

Embodiments of the present disclosure provide a charging method. Thecharging method includes: when a power adapter is coupled to a terminal,performing a rectification on a first alternating current to output afirst voltage with a first ripple waveform; modulating the first voltageby controlling a switch unit, and outputting a plurality of voltageswith ripple waveforms by a conversion of a transformer; compositing theplurality of voltages to output a second alternating current, in which,for each cycle of the second alternating current, a peak voltage of apositive half is greater than an absolute value of a valley voltage of anegative half; applying the second alternating current to a battery ofthe terminal; sampling voltage and/or current at a primary winding ofthe transformer to obtain a voltage sampling value and/or a currentsampling value; and adjusting a duty ratio of a control signal forcontrolling the switch unit according to the voltage sampling valueand/or the current sampling value, such that the second alternatingvoltage meets a charging requirement when the power adapter is coupledto the terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a charging system accordingto embodiments of the present disclosure.

FIG. 2 is a schematic diagram illustrating a compositing unit accordingto an embodiment of the present disclosure.

FIG. 3 is a schematic diagram illustrating a compositing unit accordingto another embodiment of the present disclosure.

FIG. 4 is a schematic diagram illustrating a charging system by using aflyback switching power supply according to embodiments of the presentdisclosure.

FIG. 5 is a schematic diagram illustrating a waveform of a chargingvoltage outputted to a battery from a power adapter according to anembodiment of the present disclosure.

FIG. 6 is a schematic diagram illustrating a control signal outputted toa switch unit according to an embodiment of the present disclosure.

FIG. 7 is a schematic diagram illustrating a second charging processaccording to an embodiment of the present disclosure.

FIG. 8 is a schematic diagram illustrating a charging system accordingto an embodiment of the present disclosure.

FIG. 9 is a schematic diagram illustrating a charging system accordingto an embodiment of the present disclosure.

FIG. 10 is a schematic diagram illustrating a charging system accordingto another embodiment of the present disclosure.

FIG. 11 is a schematic diagram illustrating a charging system accordingto yet another embodiment of the present disclosure.

FIG. 12 is a block diagram of a sampling unit according to an embodimentof the present disclosure.

FIG. 13 is a schematic diagram illustrating a charging system accordingto an embodiment of the present disclosure.

FIG. 14 is a schematic diagram illustrating a terminal according to anembodiment of the present disclosure.

FIG. 15 is a schematic diagram illustrating a terminal according toanother embodiment of the present disclosure.

FIG. 16 is a flow chart of a charging method according to embodiments ofthe present disclosure.

FIG. 17 is a block diagram of a charging device according to embodimentsof the present disclosure.

FIG. 18 is a block diagram of a power adapter according to an embodimentof the present disclosure.

FIG. 19 is a block diagram of a terminal according to an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Descriptions will be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in drawings, in which thesame or similar elements and the elements having same or similarfunctions are denoted by like reference numerals throughout thedescriptions. The embodiments described herein with reference todrawings are explanatory, are intended to understand the presentdisclosure, and are not construed to limit the present disclosure.

The present disclosure is made based on following understanding andresearches.

The inventors find that, during a charging to a battery of a mobileterminal by a power adapter, with the increasing of power of the poweradapter, it is easy to cause an increase in polarization resistance ofthe battery and temperature of the battery, thus reducing a service lifeof the battery, and affecting a reliability and a safety of the battery.

Moreover, most devices cannot work directly with alternating currentwhen the power is usually supplied with the alternating current, becausethe alternating current such as mains supply of 220V and 50 Hz outputselectric energy discontinuously. In order to avoid the discontinuity, itneeds to use an electrolytic condenser to store the electric energy,such that when the power supply is in the trough period, it is possibleto depend on the electric energy stored in the electrolytic condenser toensure a continue and stable power supply. Thus, when an alternatingcurrent power source charges the mobile terminal via the power adapter,the alternating current such as the alternating current of 220V providedby the alternating current power source is converted into stable directcurrent, and the stable direct current is provided to the mobileterminal. However, the power adapter charges the battery in the mobileterminal so as to supply power to the mobile terminal indirectly, andthe continuity of power supply can be guaranteed by the battery, suchthat it is unnecessary for the power adapter to output stable andcontinue direct current when charging the battery.

Accordingly, a first objective of the present disclosure is to provide acharging system, which enables a second alternating current outputted bya power adapter to meet a charging requirement and to be applieddirectly to a battery of the terminal directly, thus realizing aminiaturization and low cost of the power adapter, and prolonging aservice life of the battery.

A second objective of the present disclosure is to provide a poweradapter. A third objective of the present disclosure is to provide acharging method.

In the following, a charging system, a power adapter and a chargingmethod provided in embodiments of the present disclosure will bedescribed with reference to drawings.

Referring to FIGS. 1-15, the charging system may include a battery 202,a first rectifier 101, a switch unit 102, a transformer 103, acompositing unit 104, a sampling unit 106, and a control unit 107.

The first rectifier 101 is configured to rectify a first alternatingcurrent and output a first voltage with a first ripple waveform. Theswitch unit 102 is configured to modulate the first voltage according toa control signal and output a modulated first voltage. The transformer103 is configured to output a plurality of voltages with ripplewaveforms according to the modulated first voltage. The compositing unit104 is configured to composite the plurality of voltages to output asecond alternating current. For each cycle of the second alternatingcurrent, a peak voltage of a positive half is greater than an absolutevalue of a valley voltage of a negative half. The sampling unit 106 isconfigured to sample voltage and/or current at a primary winding of thetransformer to obtain a voltage sampling value and/or a current samplingvalue. The control unit 107 is coupled to the sampling unit 106 and theswitch unit 102 respectively. The control unit 107 is configured tooutput the control signal to the switch unit 102, to adjust a duty ratioof the control signal according to the current sampling value and/or thevoltage sampling value, such that the second alternating current meets acharging requirement of the battery 202.

In at least one embodiment of the present disclosure, part or allstructure (hardware and software) of the adapter can be integrated intothe terminal. Integrated structure of the adapter and the terminal canbe called as the charging system of the present disclosure, or called asa terminal.

In an embodiment of the present disclosure, the charging system for theterminal provided in embodiments of the present disclosure includes apower adapter 1 and a terminal 2. The battery may be a component in aterminal 2. The first rectifier, the switch unit, the transformer, thesecond rectifier, the sampling unit and the control unit may be disposedin a power adapter 1.

As illustrated in FIG. 1, the power adapter 1 includes a first rectifier101, a switch unit 102, a transformer 103, a compositing unit 104, asampling unit 106, and a control unit 107. The first rectifier 101 isconfigured to rectify an input alternating current i.e. the firstalternating current (mains supply, for example AC 220V) to output afirst voltage with a first ripple waveform, for example a voltage with asteamed bun waveform. As illustrated in FIG. 4, the first rectifier 101may be a full-bridge rectifier circuit formed of four diodes. The switchunit 102 is configured to modulate the first voltage with the firstripple waveform according to a control signal to output a modulatedfirst voltage. The switch unit 102 may be formed of MOS transistors. APWM (Pulse Width Modulation) control is performed on the MOS transistorsto perform a chopping modulation on the voltage with the steamed bunwaveform.

The transformer 103 is configured to output a plurality of voltages withripple waveforms according to the modulated first voltage. Thecompositing unit 104 is configured to composite the plurality ofvoltages to output a second alternating current. For each cycle of thesecond alternating current, a peak voltage of a positive half is greaterthan an absolute value of a valley voltage of a negative half. Thesecond alternating current is configured to be introduced into aterminal to charge a battery in the terminal when the power adapter iscoupled to the terminal. A voltage waveform of the second alternatingcurrent may be illustrated in FIG. 5.

In an embodiment of the present disclosure, as illustrated in FIG. 4,the power adapter may adopt a flyback switch unit. The transformer 103includes a primary winding, a first secondary winding and a secondsecondary winding. An end of the primary winding is coupled to a firstoutput end of the first rectifier 101. A second output end of the firstrectifier 101 is grounded. Another end of the primary winding is coupledto the switch unit 102 (for example, if the switch unit 102 is a MOStransistor, the other end of the primary winding is coupled to a drainof the MOS transistor). The first secondary winding and the secondsecondary winding both are coupled to the compositing unit 104. Thetransformer 103 is configured to output a second voltage with a secondripple waveform via the first secondary winding according to themodulated first voltage and to output a third voltage with a thirdripple waveform via the second secondary winding according to themodulated first voltage. The compositing unit 104 is configured tocomposite the second voltage and the third voltage to output the secondalternating current.

In embodiments of the present disclosure, as illustrated in FIG. 2 orFIG. 3 the compositing unit 104 may include two controllable switchcircuits formed of electronic switch components such as MOS transistors,and a control module configured to control the two controllable switchcircuits to switch on or off. The two controllable switch circuits arecontrolled to be switched on or off alternately. For example, when thecontrol module controls one of the controllable switch circuits toswitch on and the other of the controllable switch circuits to switchoff, the compositing unit 104 outputs a half cycle of the secondalternating current; when the control module controls the one of thecontrollable switch circuits to switch off and the other of thecontrollable switch circuits to switch on, the compositing unit 104outputs the other half cycle of the second alternating current.Certainly, in other embodiments of the present disclosure, the controlmodule herein may also employ the control unit 107 described above, forexample as illustrated in FIG. 3.

The transformer 103 is a high-frequency transformer of which a workingfrequency ranges from 50 KHz to 2 MHz. The high-frequency transformer isconfigured to couple the modulated first voltage to the secondary sideso as to output via the secondary winding for example the firstsecondary winding and the second secondary winding. In embodiments ofthe present disclosure, with the high-frequency transformer, acharacteristic of a small size compared to the low-frequency transformer(also known as an industrial frequency transformer, mainly used in thefrequency of mains supply such as alternating current of 50 Hz or 60 Hz)may be exploited to realize miniaturization of the power adapter 1.

As illustrated in FIG. 1 or FIG. 4, the sampling unit 106 is configuredto sample voltage and/or current at the primary winding of thetransformer to obtain a voltage sampling value and/or a current samplingvalue, i.e. the voltage sampling value and/or the current sampling valuemay be obtained by sampling at the primary winding. The control unit 107is coupled to the sampling unit 106 and the switch unit 102respectively. The control unit 107 is configured to output the controlsignal to the switch unit 102, and to adjust a duty ratio of the controlsignal according to the current sampling value and/or the voltagesampling value, such that the second alternating current meets acharging requirement of the terminal 2 when the power adapter 1 iscoupled to the terminal 2.

Further, in an embodiment of the present disclosure, the power adapterfurther includes a first charging interface 105. The first charginginterface 105 is coupled to an output end of the compositing unit 104,and configured to apply the second alternating current to a battery in aterminal when the first charging interface is coupled to the terminal.

As illustrated in FIG. 1, the terminal 2 includes a battery 202. Thesecond alternating current is configured to be introduced into aterminal to charge a battery in the terminal when the power adapter iscoupled to the terminal.

In an embodiment, the terminal 2 further includes a second charginginterface 201. The second charging interface 201 is coupled to thebattery 202. When the second charging interface 201 is coupled to thefirst charging interface 105, the second charging interface 201 isconfigured to apply the second alternating current to the battery 202,so as to charge the battery 202.

In an embodiment, the second alternating current meeting the chargingrequirement means that, a peak voltage/an average voltage and a peakcurrent/an average current of the second alternating current meet thecharging voltage and charging current when the battery is chargedcorrespondingly. In other words, the control unit 107 is configured toadjust the duty ratio of the control signal (such as a PWM signal)according to voltage and/or current (i.e., voltage and/or current of thesecond alternating current) outputted by the power adapter 1 andobtained by sampling at the primary side, so as to adjust the output ofthe compositing unit 104 in real time and realize a closed-loopadjusting control, such that the second alternating current meets thecharging requirement of the terminal 2, thus ensuring the stable andsafe charging of the battery. In detail, a waveform of a chargingvoltage outputted to a battery is illustrated in FIG. 5, in which thewaveform of the charging voltage is adjusted according to the duty ratioof the PWM signal.

It can be understood that, when adjusting the duty ratio of the PWMsignal, an adjusting instruction may be generated according to thevoltage sampling value, or according to the current sampling value, oraccording to the voltage sampling value and the current sampling value.

Therefore, in embodiments of the present disclosure, by controlling theswitch unit 102, a PWM chopping modulation is directly performed on thefirst voltage with the first ripple waveform i.e. the steamed bunwaveform after a full-bridge rectification, and then a modulated voltageis sent to the high-frequency transformer and is coupled from theprimary side to the secondary side via the high-frequency transformer,and is subject to a waveform composition or splicing of the compositingunit to output the second alternating current with the alternatingwaveform. The second alternating current is applied to the batterydirectly so as to realize fast charging (which is described as thesecond charging in the following) to the battery. The voltage amplitudeof the second alternating current may be adjusted according to the dutyratio of the PWM signal, such that the output of the power adapter maymeet the charging requirement of the battery. It can be seen from that,the power adapter according to embodiments of the present disclosure,without providing electrolytic condensers at the primary side and thesecondary side, may directly charge the battery via the voltage with thealternating current waveform, such that a size of the power adapter maybe reduced, thus realizing miniaturization of the power adapter, anddecreasing cost greatly.

In an embodiment of the present disclosure, the control unit 107 may bean MCU (micro controller unit), which means that the control unit 107may be a micro processor integrated with a switch driving controlfunction, a voltage and current adjusting control function.

According to an embodiment of the present disclosure, the control unit107 is further configured to adjust a frequency of the control signalaccording to the voltage sampling value and/or the current samplingvalue. That is, the control unit 107 is further configured to control tooutput the PWM signal to the switch unit 102 for a continuous timeperiod, and then to stop outputting for a predetermined time period andthen to restart to output the PWM signal. In this way, the voltageapplied to the battery is intermittent, thus realizing the intermittentcharging of the battery, which avoids a safety hazard caused by heatingphenomenon occurring when the battery is charged continuously andimproves the reliability and safety of the charging to the battery.

Under a low temperature condition, since the conductivity of ions andelectrons in a lithium battery decreases, it is prone to intensifydegree of polarization during a charging process for the lithiumbattery. A continuous charging not only makes this polarization seriousbut also increases a possibility of lithium precipitation, thusaffecting safety performance of the battery. Furthermore, the continuouscharging may accumulate heat generated due to the charging, thus leadingto an increasing of internal temperature of the battery. When thetemperature exceeds a certain value, performance of the battery may belimited, and possibility of safety hazard is increased.

In embodiments of the present disclosure, by adjusting the frequency ofthe control signal, the power adapter outputs intermittently, whichmeans that a battery resting process is introduced into the chargingprocess, such that the lithium precipitation due to the polarizationduring the continuous charging is reduced and continuous accumulation ofgenerated heat may be avoided to realize drop in the temperature, thusensuring the safety and reliability of charging to the battery.

The control signal outputted to the switch unit 102 is illustrated inFIG. 6, for example. Firstly, the PWM signal is outputted for acontinuous time period, then output of the PWM signal is stopped for acertain time period, and then the PWM signal is outputted for acontinuous time period again. In this way, the control signal output tothe switch unit 102 is intermittent, and the frequency is adjustable.

As illustrated in FIG. 4, the control unit 107 is coupled to the firstcharging interface 105. The control unit 107 is further configured toobtain status information of the terminal 2 by performing acommunication with the terminal 2 via the first charging interface 105.In this way, the control unit 107 is further configured to adjust theduty ratio of the control signal (such as the PWM signal) according tothe status information of the terminal, the voltage sampling valueand/or the current sampling value.

The status information of the terminal includes an electric quantity ofthe battery, a temperature of the battery, a voltage/current of thebattery of the terminal, interface information of the terminal andinformation on a path impedance of the terminal.

In detail, the first charging interface 105 includes a power wire and adata wire. The power wire is configured to charge the battery. The datawire is configured to communicate with the terminal. When the secondcharging interface 201 is coupled to the first charging interface 105,communication query instructions may be transmitted by the power adapter1 and the terminal 2 to each other. A communication connection can beestablished between the power adapter 1 and the terminal 2 afterreceiving a corresponding reply instruction. The control unit 107 mayobtain the status information of the terminal 2, so as to negotiatedwith the terminal 2 about a charging mode and charging parameters (suchas the charging current, the charging voltage) and to control thecharging process.

The charging mode supported by the power adapter and/or the terminal mayinclude a first charging mode and a second charging mode. A chargingspeed of the second charging mode is faster than that of the firstcharging mode. For example, a charging current of the second chargingmode is greater than that of the first charging mode. In general, thefirst charging mode may be understood as a charging mode in which arated output voltage is 5V and a rated output current is less than orequal to 2.5 A. In addition, in the first charging mode, D+ and D− inthe data wire of an output port of the power adapter may beshort-circuited. On the contrary, in the second charging mode accordingto embodiments of the present disclosure, the power adapter may realizedata exchange by communicating with the terminal via D+ and D− in thedata wire, i.e., second charging instructions may be sent by the poweradapter and the terminal to each other. The power adapter sends a secondcharging query instruction to the terminal. After receiving a secondcharging reply instruction from the terminal, the power adapter obtainsthe status information of the terminal and starts the second chargingmode according to the second charging reply instruction. The chargingcurrent in the second charging mode may be greater than 2.5 A, forexample, may be 4.5 A or more. The first charging mode is not limited inembodiments of the present disclosure. As long as the power adaptersupports two charging modes one of which has a charging speed (orcurrent) greater than the other charging mode, the charging mode with aslower charging speed may be regarded as the first charging mode. As tothe charging power, the charging power in the second charging mode maybe greater than or equal to 15 W.

The first charging mode is a normal charging mode and the secondcharging mode is a fast charging mode. Under the normal charging mode,the power adapter outputs a relatively small current (typically lessthan 2.5 A) or charges the battery in the mobile terminal with arelatively small power (typically less than 15 W). While, under the fastcharge mode, the power adapter outputs a relatively large current(typically greater than 2.5 A, such as 4.5 A, 5 A or higher) or chargesthe battery in the mobile terminal with a relatively large power(typically greater than or equal to 15 W), compared to the normalcharging mode. In the normal charging mode, it may take several hours tofully fill a larger capacity battery (such as a battery with 3000 mAh),while in the fast charging mode, the period of time may be significantlyshortened when the larger capacity battery is fully filled, and thecharging is faster.

The control unit 107 communicates with the terminal 2 via the firstcharging interface 105 to determine the charging mode. The charging modeincludes the second charging mode and the first charging mode.

In detail, the power adapter is coupled to the terminal via a universalserial bus (USB) interface. The USB interface may be a general USBinterface, or a micro USB interface. A data wire in the USB interface isconfigured as the data wire in the first charging interface, andconfigured for a bidirectional communication between the power adapterand the terminal. The data wire may be D+ and/or D− wire in the USBinterface. The bidirectional communication may refer to an informationinteraction performed between the power adapter and the terminal.

The power adapter performs the bidirectional communication with theterminal via the data wire in the USB interface, so as to determine tocharge the terminal in the second charging mode.

In an embodiment, during a process that the power adapter and theterminal negotiate whether to charge the terminal in the second chargingmode, the power adapter may only keep a coupling with the terminal butdoes not charge the terminal, or charges the terminal in the firstcharging mode or charges the terminal with small current, which is notlimited herein.

The power adapter adjusts a charging current to a charging currentcorresponding to the second charging mode, and charges the terminal.After determining to charge the terminal in the second charging mode,the power adapter may directly adjust the charging current to thecharging current corresponding to the second charging mode or maynegotiate with the terminal about the charging current of the secondcharging mode. For example, the charging current corresponding to thesecond charging mode may be determined according to a current electricquantity of the battery of the terminal.

In embodiments of the present disclosure, the power adapter does notincrease the output current blindly for second charging, but needs toperform the bidirectional communication with the terminal so as tonegotiate whether to adopt the second charging mode. In contrast to therelated art, the safety of second charging is improved.

As an embodiment, when the control unit 107 performs the bidirectionalcommunication with the terminal via the first charging interface so asto determine to charge the terminal in the second charging mode, thecontrol unit 107 is configured to send a first instruction to theterminal and to receive a first reply instruction from the terminal. Thefirst instruction is configured to query the terminal whether to startthe second charging mode. The first reply instruction is configured toindicate that the terminal agrees to start the second charging mode.

As an embodiment, before the control unit sends the first instruction tothe terminal, the power adapter is configured to charge the terminal inthe first charging mode. The control unit is configured to send thefirst instruction to the terminal when determining that a chargingduration of the first charging mode is greater than a predeterminedthreshold.

In an embodiment, when the power adapter determines that the chargingduration of the first charging mode is greater than the predeterminedthreshold, the power adapter may determine that the terminal hasidentified it as a power adapter, such that the second charging querycommunication may start.

As an embodiment, after determining the terminal is charged for apredetermined time period with a charging current greater than or equalto a predetermined current threshold, the power adapter is configured tosend the first instruction to the terminal.

As an embodiment, the control unit is further configured to control thepower adapter to adjust a charging current to a charging currentcorresponding to the second charging mode by controlling the switchunit. Before the power adapter charges the terminal with the chargingcurrent corresponding to the second charging mode, the control unit isconfigured to perform the bidirectional communication with the terminalvia the data wire of the first charging interface to determine acharging voltage corresponding to the second charging mode, and tocontrol the power adapter to adjust a charging voltage to the chargingvoltage corresponding to the second charging mode.

As an embodiment, when the control unit performs the bidirectionalcommunication with the terminal via the data wire of the first charginginterface to determine the charging voltage corresponding to the secondcharging mode, the control unit is configured to send a secondinstruction to the terminal, to receive a second reply instruction sentfrom the terminal, and to determine the charging voltage correspondingto the second charging mode according to the second reply instruction.The second instruction is configured to query whether a current outputvoltage of the power adapter is suitable for being used as the chargingvoltage corresponding to the second charging mode. The second replyinstruction is configured to indicate that the current output voltage ofthe power adapter is suitable, high or low.

As an embodiment, before controlling the power adapter to adjust thecharging current to the charging current corresponding to the secondcharging mode, the control unit is further configured to perform thebidirectional communication with the terminal via the data wire of thefirst charging interface to determine the charging current correspondingto the second charging mode.

As an embodiment, when performing the bidirectional communication withthe terminal via the data wire of the first charging interface todetermine the charging current corresponding to the second chargingmode, the control unit is configured to send a third instruction to theterminal, to receive a third reply instruction sent from the terminaland to determine the charging current corresponding to the secondcharging mode according to the third reply instruction. The thirdterminal is configured to query a maximum charging current supported bythe terminal. The third reply instruction is configured to indicate themaximum charging current supported by the terminal.

The power adapter may determine the above maximum charging current asthe charging current corresponding to the second charging mode, or mayset the charging current as a charging current less than the maximumcharging current.

As an embodiment, during a process that the power adapter charges theterminal in the second charging mode, the control unit is furtherconfigured to perform the bidirectional communication with the terminalvia the data wire of the first charging interface, so as to continuouslyadjust a charging current outputted to the battery from the poweradapter by controlling the switch unit.

The power adapter may query the status information of the terminalcontinuously, for example, query the voltage of the battery of theterminal, the electric quantity of the battery, etc., so as to adjustthe charging current outputted to the battery from the power adaptercontinuously.

As an embodiment, when the control unit performs the bidirectionalcommunication with the terminal via the data wire of the first charginginterface to continuously adjust the charging current outputted to thebattery from the power adapter by controlling the switch unit, thecontrol unit is configured to send a fourth instruction to the terminal,to receive a fourth reply instruction sent by the terminal, and toadjust the charging current output from the power adapter to the batteryby controlling the switch unit according to the current voltage of thebattery. The fourth instruction is configured to query a current voltageof the battery in the terminal. The fourth reply instruction isconfigured to indicate the current voltage of the battery in theterminal.

As an embodiment, the control unit is configured to adjust the chargingcurrent outputted to the battery from the power adapter to a chargingcurrent value corresponding to the current voltage of the battery bycontrolling the switch unit according to the current voltage of thebattery and a predetermined correspondence between battery voltagevalues and charging current values.

In detail, the power adapter may store the correspondence betweenbattery voltage values and charging current values in advance. The poweradapter may also perform the bidirectional communication with theterminal via the data wire of the first charging interface to obtainfrom the terminal the correspondence between battery voltage values andcharging current values stored in the terminal.

As an embodiment, during the process that the power adapter charges theterminal in the second charging mode, the control unit is furtherconfigured to determine whether there is a poor contact between thefirst charging interface and the second charging interface by performingthe bidirectional communication with the terminal via the data wire ofthe first charging interface. When determining that there is the poorcontact between the first charging interface and the second charginginterface, the control unit is configured to control the power adapterto quit the second charging mode.

As an embodiment, before determining whether there is the poor contactbetween the first charging interface and the second charging interface,the control unit is further configured to receive information indicatinga path impedance of the terminal from the terminal. The control unit isconfigured to send a fourth instruction to the terminal. The fourthinstruction is configured to query a current voltage of the battery inthe terminal. The control unit is configured to receive a fourth replyinstruction sent by the terminal. The fourth reply instruction isconfigured to indicate the current voltage of the battery in theterminal. The control unit is configured to determine a path impedancefrom the power adapter to the battery according to an output voltage ofthe power adapter and the current voltage of the battery and determineswhether there is the poor contact between the first charging interfaceand the second charging interface according to the path impedance fromthe power adapter to the battery, the path impedance of the terminal,and a path impedance of a charging wire between the power adapter andthe terminal.

The terminal may record the path impedance thereof in advance. Forexample, since the terminals in a same type have a same structure, thepath impedance of the terminals in the same type is set to a same valuewhen configuring factory settings. Similarly, the power adapter mayrecord the path impedance of the charging wire in advance. When thepower adapter obtains the voltage cross two ends of the battery of theterminal, the path impedance of the whole path can be determinedaccording to the voltage drop cross two ends of the battery and currentof the path. When the path impedance of the whole path>the pathimpedance of the terminal+the path impedance of the charging wire, orthe path impedance of the whole path−(the path impedance of theterminal+the path impedance of the charging wire)>an impedancethreshold, it can be considered that there is the poor contact betweenthe first charging interface and the second charging interface.

As an embodiment, before the power adapter quits the second chargingmode, the control unit is further configured to send a fifth instructionto the terminal. The fifth instruction is configured to indicate thatthere is the poor contact between the first charging interface and thesecond charging interface.

After sending the fifth instruction, the power adapter may quit thesecond charging mode or reset.

The second charging process according to embodiments of the presentdisclosure is described from the perspective of the power adapter, andthen the second charging process according to embodiments of the presentdisclosure will be described from the perspective of the terminal in thefollowing.

In an embodiment, the interaction between the power adapter and theterminal, relative characteristics, functions described at the terminalside correspond to descriptions at the power adapter side, thusrepetitive description will be omitted for simplification.

According to an embodiment of the present disclosure, as illustrated inFIG. 14, the terminal 2 further includes a charging control switch 203and a controller 204. The charging control switch 203, such as a switchcircuit formed of an electronic switch element, is coupled between thesecond charging interface 201 and the battery 202, and is configured toswitch on or off a charging process of the battery under a control ofthe controller 204. In this way, the charging process of the battery canbe controlled at the terminal side, thus ensuring the safety andreliability of charging to battery.

As illustrated in FIG. 15, the terminal 2 further includes acommunication unit 205. The communication unit 205 is configured toestablish a bidirectional communication between the controller 204 andthe control unit 107 via the second charging interface 201 and the firstcharging interface 105. In other words, the terminal and the poweradapter can perform the bidirectional communication via the data wire inthe USB interface. The terminal supports the first charging mode and thesecond charging mode. The charging current of the second charging modeis greater than that of the first charging mode. The controller isconfigured to perform the bidirectional communication with the controlunit via the communication unit such that the power adapter determinesto charge the terminal in the second charging mode, and the control unitcontrols the power adapter to output according to the charging currentcorresponding to the second charging mode, for charging the battery inthe terminal.

In embodiments of the present disclosure, the power adapter does notincrease the output current blindly for the second charging, but needsto perform the bidirectional communication with the terminal tonegotiate whether to adopt the second charging mode. In contrast to therelated art, the safety of the second charging process is improved.

As an embodiment, the controller is configured to receive the firstinstruction sent by the control unit via the communication unit. Thefirst instruction is configured to query the terminal whether to startthe second charging mode. The controller is configured to send a firstreply instruction to the control unit via the communication unit. Thefirst reply instruction is configured to indicate that the terminalagrees to start the second charging mode.

As an embodiment, before the controller receives the first instructionsent by the control unit via the communication unit, the battery in theterminal is charged by the power adapter in the first charging mode.When the control unit determines that a charging duration of the firstcharging mode is greater than a predetermined threshold, the controlunit sends the first instruction to the communication unit in theterminal, and the controller receives the first instruction sent by thecontrol unit via the communication unit.

As an embodiment, before the power adapter outputs according to thecharging current corresponding to the second charging mode for chargingthe battery in the terminal, the controller is configured to perform thebidirectional communication with the control unit via the communicationunit, such that the power adapter determines the charging voltagecorresponding to the second charging mode.

As an embodiment, the controller is configured to receive a secondinstruction sent by the control unit, and to send a second replyinstruction to the control unit. The second instruction is configured toquery whether a current output voltage of the power adapter is suitablefor being used as the charging voltage corresponding to the secondcharging mode. The second reply instruction is configured to indicatethat the current output voltage of the power adapter is suitable, highor low.

As an embodiment, the controller is configured to perform thebidirectional communication with the control unit, such that the poweradapter determines the charging current corresponding to the secondcharging mode.

The controller is configured to receive a third instruction sent by thecontrol unit, in which the third instruction is configured to query amaximum charging current supported by the terminal. The controller isconfigured to send a third reply instruction to the control unit, inwhich the third reply instruction is configured to indicate the maximumcharging current supported by the terminal, such that the power adapterdetermines the charging current corresponding to the second chargingmode according to the maximum charging current.

As an embodiment, during a process that the power adapter charges theterminal in the second charging mode, the controller is configured toperform the bidirectional communication with the control unit, such thatthe power adapter continuously adjusts a charging current outputted tothe battery.

The controller is configured to receive a fourth instruction sent by thecontrol unit, in which the fourth instruction is configured to query acurrent voltage of the battery in the terminal. The controller isconfigured to send a fourth reply instruction to the control unit, inwhich the fourth reply instruction is configured to indicate the currentvoltage of the battery in the terminal, such that the power adaptercontinuously adjusts the charging current outputted to the batteryaccording to the current voltage of the battery.

As an embodiment, during the process that the power adapter charges theterminal in the second charging mode, the controller is configured toperform the bidirectional communication with the commutation unit, suchthat the power adapter determines whether there is a poor contactbetween the first charging interface and the second charging interface.

The controller receives a fourth instruction sent by the control unit.The fourth instruction is configured to query a current voltage of thebattery in the terminal. The controller sends a fourth reply instructionto the control unit, in which the fourth reply instruction is configuredto indicate the current voltage of the battery in the terminal, suchthat the control unit determines whether there is the poor contactbetween the first charging interface and the second charging interfaceaccording to an output voltage of the power adapter and the currentvoltage of the battery.

As an embodiment, the controller is configured to receive a fifthinstruction sent by the control unit. The fifth instruction isconfigured to indicate that there is the poor contact between the firstcharging interface and the second charging interface.

In order to initiate and adopt the second charging mode, the poweradapter may perform a second charging communication procedure with theterminal, for example, by one or more handshakes, so as to realize thesecond charging of battery. Referring to FIG. 7, the second chargingcommunication procedure according to embodiments of the presentdisclosure and respective stages in the second charging process will bedescribed in detail. Communication actions or operations illustrated inFIG. 7 are merely exemplary. Other operations or various modificationsof respective operations in FIG. 7 can be implemented in embodiments ofthe present disclosure. In addition, respective stages in FIG. 7 may beexecuted in an order different from that illustrated in FIG. 7, and itis unnecessary to execute all the operations illustrated in FIG. 7. Acurve in FIG. 7 represents a variation trend of a peak value or a meanvalue of the charging current, rather than a curve of actual chargingcurrent.

As illustrated in FIG. 7, the second charging process may include thefollowing five stages.

Stage 1:

After being coupled to a power supply providing device, the terminal maydetect a type of the power supply providing device via the data wire D+and D−. When detecting that the power supply providing device is a poweradapter, the terminal may absorb current greater than a predeterminedcurrent threshold I2, such as 1. When the power adapter detects thatcurrent outputted by the power adapter is greater than or equal to I2within a predetermined time period (such as a continuous time periodT1), the power adapter determines that the terminal has completed therecognition of the type of the power supply providing device. The poweradapter initiates a handshake communication between the power adapterand the terminal, and sends an instruction 1 (corresponding to theabove-mentioned first instruction) to query the terminal whether tostart the second charging mode (or flash charging).

When receiving a reply instruction indicating that the terminaldisagrees to start the second charging mode from the terminal, the poweradapter detects the output current of the power adapter again. When theoutput current of the power adapter is still greater than or equal to I2within a predetermined continuous time period (such as a continuous timeperiod T1), the power adapter initiates a request again to query theterminal whether to start the second charging model. The above actionsin stage 1 are repeated, until the terminal replies that it agrees tostart the second charging mode or the output current of the poweradapter is no longer greater than or equal to I2.

After the terminal agrees to start the second charging mode, the secondcharging process is initiated, and the second charging communicationprocedure goes into stage 2.

Stage 2:

For the voltage with the steamed bun waveform outputted by the poweradapter, there may be several levels. The power adapter sends aninstruction 2 (corresponding to the above-mentioned second instruction)to the terminal to query the terminal whether the output voltage of thepower adapter matches to the current voltage of the battery (or whetherthe output voltage of the power adapter is suitable, i.e., suitable forthe charging voltage in the second charging mode), i.e., whether theoutput voltage of the power adapter meets the charging requirement.

The terminal replies that the output voltage of the power adapter ishigher, lower or suitable. When the power adapter receives a feedbackindicating that the output voltage of the power adapter is lower orhigher from the terminal, the control unit adjusts the output voltage ofthe power adapter by one level by adjusting the duty ratio of the PWMsignal, and sends the instruction 2 to the terminal again to query theterminal whether the output voltage of the power adapter matches.

The above actions in stage 2 are repeated, until the terminal replies tothe power adapter that the output voltage of the power adapter is at amatching level. And then the second charging communication proceduregoes into stage 3.

Stage 3:

After the power adapter receives the feedback indicating that the outputvoltage of the power adapter matches from the terminal, the poweradapter sends an instruction 3 (corresponding to the above-mentionedthird instruction) to the terminal to query the maximum charging currentsupported by the terminal. The terminal returns to the power adapter themaximum charging current supported by itself, and then the secondcharging communication procedure goes into stage 4.

Stage 4:

After receiving a feedback indicating the maximum charging currentsupported by the terminal from the terminal, the power adapter may setan output current reference value. The control unit 107 adjusts the dutyratio of the PWM signal according to the output current reference value,such that the output current of the power adapter meets the chargingcurrent requirement of the terminal, and the second chargingcommunication procedure goes into constant current stage. The constantcurrent stage means that the peak value or mean value of the outputcurrent of the power adapter basically remains unchanged (which meansthat the variation amplitude of the peak value or mean value of theoutput current is very small, for example within a range of 5% of thepeak value or mean value of the output current), namely, the peak valueof the second alternating current keeps constant in each period.

Stage 5:

When the second charging communication procedure goes into the constantcurrent stage, the power adapter sends an instruction 4 (correspondingto the above-mentioned fourth instruction) at intervals to query thecurrent voltage of battery in the terminal. The terminal may feedback tothe power adapter the current voltage of the battery, and the poweradapter may determine according to the feedback of the current voltageof the battery whether there is a poor USB contact (i.e., a poor contactbetween the first charging interface and the second charging interface)and whether it is necessary to decrease the charging current value ofthe terminal. When the power adapter determines that there is the poorUSB contact, the power adapter sends an instruction 5 (corresponding tothe above-mentioned fifth instruction), and then the power adapter isreset, such that the second charging communication procedure goes intostage 1 again.

In some embodiments of the present disclosure, in stage 1, when theterminal replies to the instruction 1, data corresponding to theinstruction 1 may carry data (or information) on the path impedance ofthe terminal. The data on the path impedance of the terminal may be usedin stage 5 to determine whether there is the poor USB contact.

In some embodiments of the present disclosure, in stage 2, the timeperiod from when the terminal agrees to start the second charging modeto when the power adapter adjusts the voltage to a suitable value may belimited in a certain range. If the time period exceeds a predeterminedrange, the terminal may determine that there is an exception request,thus a quick reset is performed.

In some embodiments of the present disclosure, in stage 2, the terminalmay give a feedback indicating that the output voltage of the poweradapter is suitable/matches to the power adapter when the output voltageof the power adapter is adjusted to a value higher than the currentvoltage of the battery by ΔV (ΔV is about 200-500 mV). When the terminalgives a feedback indicating that the output voltage of the power adapteris not suitable (higher or lower) to the power adapter, the control unit107 adjusts the duty ratio of the PWM signal according to the voltagesampling value, so as to adjust the output voltage of the power adapter.

In some embodiments of the present disclosure, in stage 4, the adjustingspeed of the output current value of the power adapter may be controlledto be in a certain range, thus avoiding an abnormal interruption of thesecond charging due to the too fast adjusting speed.

In some embodiments of the present disclosure, in stage 5, the variationamplitude of the output current value of the power adapter may becontrolled to be within 5%, i.e., stage 5 may be regarded as theconstant current stage.

In some embodiments of the present disclosure, in stage 5, the poweradapter monitors the impedance of a charging loop in real time, i.e.,the power adapter monitors the impedance of the whole charging loop bymeasuring the output voltage of the power adapter, the charging currentand the read-out voltage of the battery in the terminal. When theimpedance of the charging loop>the path impedance of the terminal+theimpedance of the second charging data wire, it may be considered thatthere is the poor USB contact, and thus a second charging reset isperformed.

In some embodiments of the present disclosure, after the second chargingmode is started, a time interval of communications between the poweradapter and the terminal may be controlled to be in a certain range,such that the second charging reset can be avoided.

In some embodiments of the present disclosure, the termination of thesecond charging mode (or the second charging process) may be arecoverable termination or an unrecoverable termination.

For example, when the terminal detects that the battery is fully chargedor there is the poor USB contact, the second charging is stopped andreset, and the second charging communication procedure goes intostage 1. When the terminal disagrees to start the second charging mode,the second charging communication procedure would not go into stage 2,thus the termination of the second charging process may be considered asan unrecoverable termination.

For another example, when an exception occurs in the communicationbetween the terminal and the power adapter, the second charging isstopped and reset, and the second charging communication procedure goesinto stage 1. After requirements for stage 1 are met, the terminalagrees to start the second charging mode to recover the second chargingprocess, thus the termination of the second charging process may beconsidered as a recoverable termination.

For another example, when the terminal detects an exception occurring inthe battery, the second charging is stopped and reset, and the secondcharging communication procedure goes into stage 1. After the secondcharging communication procedure goes into stage 1, the terminaldisagrees to start the second charging mode. Till the battery returns tonormal and the requirements for stage 1 are met, the terminal agrees tostart the second charging to recover the second charging process. Thus,the termination of second charging process may be considered as arecoverable termination.

Communication actions or operations illustrated in FIG. 7 are merelyexemplary. For example, in stage 1, after the terminal is coupled to thepower adapter, the handshake communication between the terminal and thepower adapter may be initiated by the terminal. In other words, theterminal sends an instruction 1 to query the power adapter whether tostart the second charging mode (or flash charging). When receiving areply instruction indicating that the power adapter agrees to start thesecond charging mode from the power adapter, the terminal starts thesecond charging process.

Communication actions or operations illustrated in FIG. 7 are merelyexemplary. For example, after stage 5, there is a constant voltagecharging stage. In other words, in stage 5, the terminal may feedbackthe current voltage of the battery in the terminal to the power adapter.As the voltage of the battery increases continuously, the charging goesinto the constant voltage charging stage when the current voltage of thebattery reaches a constant voltage charging voltage threshold. Thecontrol unit 107 adjusts the duty ratio of the PWM signal according tothe voltage reference value (i.e., the constant voltage charging voltagethreshold), such that the output voltage of the power adapter meets thecharging voltage requirement of the terminal, i.e., the output voltageof the power adapter basically changes at a constant rate. During theconstant voltage charging stage, the charging current decreasesgradually. When the current reduces to a certain threshold, the chargingis stopped and it is illustrated that the battery is fully charged. Theconstant voltage charging refers to that the peak voltage with thesecond alternating current basically keeps constant.

In embodiments of the present disclosure, acquiring output voltage ofthe power adapter means that the peak value or mean value of the secondalternating current is acquired. Acquiring output current of the poweradapter means that the peak value or mean value of the secondalternating current is acquired.

In an embodiment of the present disclosure, as illustrated in FIG. 8,the power adapter 1 further includes a rectifying and filtering unit 109and a controllable switch 108 configured to control an operation of therectifying and filtering unit 109. The rectifying and filtering unit 109is configured to rectify and filter one of the plurality of voltages andoutput a second direct current, for example, 5V. The control unit 107 isfurther configured to, when determining the charging mode as the firstcharging mode, control the rectifying and filtering unit 109 to work bycontrolling the controllable switch 108, and control the compositingunit 104 to stop working, such that the rectifying and filtering unit109 outputs the second direct current to charge the battery; whendetermining the charging mode as the second charging mode, control therectifying and filtering unit 109 to stop working by controlling thecontrollable switch 108, and control the compositing unit 104 to work,such that the second alternating current is applied to the battery.

The rectifying and filtering unit 109 includes a rectifier diode and afiltering capacitor, which supports a standard charging of 5Vcorresponding to the first charging mode. The controllable switch 108may be formed of a semiconductor switch element such as a MOStransistor. When the power adapter charges the battery in the terminalin the first charging mode (or called as standard charging), the controlunit 107 controls the controllable switch 108 to switch on so as tocontrol the rectifying and filtering unit 109 to work. In this way, thedirect charging technology is compatible, i.e., the second directcurrent is applied to the battery in the terminal so as to realizedirect current charging of the battery. For example, in general, thefiltering part includes an electrolytic condenser and a common capacitorsuch as a small capacitor supporting standard charging of 5V (forexample, a solid-state capacitor) in parallel. Since the electrolyticcondenser occupies a bigger volume, in order to reduce the size of thepower adapter, the electrolytic condenser may be removed from the poweradapter and only one capacitor with low capacitance is left. When thefirst charging mode is adopted, a branch where the small capacitor islocated is switched on, and the current is filtered to realize a stableoutput with low power for performing a direct current charging on thebattery. When the second charging mode is adopted, the second directcurrent is output to apply to the battery, so as to realize a secondcharging of the battery.

According to an embodiment of the present disclosure, the control unit107 is further configured to obtain the charging current and/or thecharging voltage corresponding to the second charging mode according tothe status information of the terminal and to adjust the duty ratio ofthe control signal such as the PWM signal according to the chargingcurrent and/or the charging voltage corresponding to the second chargingmode, when determining the charging mode as the second charging mode. Inother words, when determining the current charging mode as the secondcharging mode, the control unit 107 obtains the charging current and/orthe charging voltage corresponding to the second charging mode accordingto the obtained status information of the terminal such as the voltage,the electric quantity and the temperature of the battery, runningparameters of the terminal and power consumption information ofapplications running on the terminal, and adjusts the duty ratio of thecontrol signal according to the charging current and/or the chargingvoltage, such that the output of the power adapter meets the chargingrequirement, thus realizing the second charging of the battery.

The status information of the terminal includes the temperature of theterminal. When the temperature of the battery is greater than a firstpredetermined temperature threshold, or the temperature of the batteryis less than a second predetermined temperature threshold, if thecurrent charging mode is the second charging mode, the second chargingmode is switched to the first charging mode. The first predeterminedtemperature threshold is greater than the second predeterminedtemperature threshold. In other words, when the temperature of thebattery is too low (for example, corresponding to less than the secondpredetermined temperature threshold) or too high (for example,corresponding to greater than the first predetermined temperaturethreshold), it is unsuitable to perform the second charging, such thatit needs to switch from the second charging mode to the first chargingmode. In embodiments of the present disclosure, the first predeterminedtemperature threshold and the second predetermined temperature thresholdcan be set according to actual situations, or can be written into thestorage of the control unit (such as the MCU of the power adapter).

In an embodiment of the present disclosure, the control unit 107 isfurther configured to control the switch unit 102 to switch off when thetemperature of the battery is greater than a predetermined hightemperature protection threshold. Namely, when the temperature of thebattery exceeds the high temperature protection threshold, the controlunit 107 needs to apply a high temperature protection strategy tocontrol the switch unit 102 to switch off, such that the power adapterstops charging the battery, thus realizing the high protection of thebattery and improving the safety of charging. The high temperatureprotection threshold may be different from or the same to the firsttemperature threshold. In an embodiment, the high temperature protectionthreshold is greater than the first temperature threshold.

In another embodiment of the present disclosure, the controller isfurther configured to obtain the temperature of the battery, and tocontrol the charging control switch to switch off (i.e., the chargingcontrol switch can be switched off at the terminal side) when thetemperature of the battery is greater than the predetermined hightemperature protection threshold, so as to stop the charging process ofthe battery and to ensure the safety of charging.

Moreover, in an embodiment of the present disclosure, the control unitis further configured to obtain a temperature of the first charginginterface, and to control the switch unit to switch off when thetemperature of the first charging interface is greater than apredetermined protection temperature. In other words, when thetemperature of the charging interface exceeds a certain temperature, thecontrol unit 107 needs to apply the high temperature protection strategyto control the switch unit 102 to switch off, such that the poweradapter stops charging the battery, thus realizing the high protectionof the battery and improving the safety of charging.

Certainly, in another embodiment of the present disclosure, thecontroller obtains the temperature of the first charging interface byperforming the bidirectional communication with the control unit. Whenthe temperature of the first charging interface is greater than thepredetermined protection temperature, the controller controls thecharging control switch to switch off, i.e., switches off the chargingcontrol switch at the terminal side, so as to stop the charging processof the battery, thus ensuring the safety of charging.

In detail, in an embodiment of the present disclosure, as illustrated inFIG. 9, the power adapter 1 further includes a driving unit 110 such asa MOSFET driver. The driving unit 110 is coupled between the switch unit102 and the control unit 107. The driving unit 110 is configured todrive the switch unit 102 to switch on or off according to the controlsignal. Certainly, in other embodiments of the present disclosure, thedriving unit 110 may also be integrated in the control unit 107.

Further, as illustrated in FIG. 10, the power adapter 1 further includesan isolation unit 111. The isolation unit 111 is coupled between thedriving unit 110 and the control unit 107, and configured to preventhigh voltages from affecting the control unit 107 at the secondary sideof the transformer 103 sending signals to or receiving signals from thedriving unit 110 at the primary side of the transformer 103, so as torealize a high-voltage isolation between the primary side and thesecondary side of the power adapter 1 (or a high-voltage isolationbetween the primary winding and the secondary winding of the transformer103). The isolation unit 111 may be implemented in an optocouplerisolation manner, or in other isolation manners. By setting theisolation unit 111, the control unit 107 may be disposed at thesecondary side of the power adapter 1 (or the secondary winding side ofthe transformer 103), such that it is convenient to communicate with theterminal 2, and the space design of the power adapter 1 becomes easierand simpler.

Certainly, in other embodiments of the present disclosure, both thecontrol unit 107 and the driving unit 110 can be disposed as the primaryside, in this way, an isolation unit 111 can be disposed between thecontrol unit 107 and the first charging interface 105 and configured toprevent high voltages from affecting the control unit 107 at thesecondary side of the transformer 103 sending signals to or receivingsignals from the first charging interface 105.

Further, in embodiments of the present disclosure, when the control unit107 is disposed at the secondary side, the isolation unit 111 isrequired, and the isolation unit 111 may be integrated in the controlunit 107. In other words, when the signal is transmitted from theprimary side to the secondary side or from the secondary side to theprimary side, an isolation unit is required to realize the high-voltageisolation.

In an embodiment of the present disclosure, as illustrated in FIG. 10,the power adapter 1 further includes an auxiliary winding and a powersupply unit 112. The auxiliary winding generates a fourth voltage with afourth ripple waveform according to the modulated first voltage. Thepower supply unit 112 is coupled to the auxiliary winding. The powersupply unit 112 (for example, including a filtering voltage regulatormodule, a voltage converting module and the like) is configured toconvert the fourth voltage with the fourth ripple waveform and output adirect current, and to supply power to the driving unit 110 and/or thecontrol unit 107 respectively. The power supply unit 112 may be formedof a small filtering capacitor, a voltage regulator chip or otherelements, performs a process and conversation on the fourth voltage withthe fourth ripple waveform and outputs the low voltage direct currentsuch as 3.3V, 5V or the like.

In other words, the power supply of the driving unit 110 can be obtainedby performing a voltage conversation on the fourth voltage with thefourth ripple waveform by the power supply unit 112. When the controlunit 107 is disposed at the primary side, the power supply of thecontrol unit 107 can also be obtained by performing a voltageconversation on the fourth voltage with the fourth ripple waveform bythe power supply unit 112. As illustrated in FIG. 10, when the controlunit 107 is disposed at the primary side, the power supply unit 112provides two lines of direct current outputs, so as to supply power tothe driving unit 110 and the control unit 107 respectively. Anoptocoupler isolation unit 111 is arranged between the control unit 107and the first charging interface 105 to realize the high-voltageisolation between the primary side and the secondary side of the poweradapter 1.

When the control unit 107 is disposed at the primary side and integratedwith the driving unit 110, the power supply unit 112 supplies power tothe control unit 107 only. When the control unit 107 is disposed at thesecondary side and the driving unit 110 is disposed at the primary side,the power supply unit 112 supplies power to the driving unit 110 only.The power supply to the control unit 107 is realized by the secondaryside, for example, a power supply unit converts the second alternatingcurrent outputted by the compositing unit 104 to direct current tosupply power to the control unit 107.

Moreover, in embodiments of the present disclosure, several smallcapacitors are coupled in parallel to the output end of first rectifier101 for filtering. Or the output end of the first rectifier 101 iscoupled to an LC filtering circuit.

In another embodiment of the present disclosure, as illustrated in FIG.11, the power adapter 1 further includes a first voltage detecting unit113. The first voltage detecting unit 113 is coupled to the auxiliarywinding and the control unit 107 respectively. The first voltagedetecting unit 113 is configured to detect the fourth voltage togenerate a voltage detecting value. The control unit 107 is furtherconfigured to adjust the duty ratio of the control signal according tothe voltage detecting value.

In other words, the control unit 107 may reflect the voltage of thesecond alternating current with the voltage outputted by the secondarywinding and detected by the first voltage detecting unit 113, and thenadjusts the duty ratio of the control signal according to the voltagedetecting value, such that the output of the compositing unit 104 meetsthe charging requirement of the battery.

In detail, in an embodiment of the present disclosure, as illustrated inFIG. 12, the sampling unit 106 includes a first current sampling circuit1061 and a first voltage sampling circuit 1062. The first currentsampling circuit 1061 is configured to sample the current at the primarywinding so as to obtain the current sampling value. The first voltagesampling circuit 1062 is configured to sample the voltage at the primarywinding so as to obtain the voltage sampling value.

In an embodiment of the present disclosure, the first current samplingcircuit 1061 can sample the current at the primary winding by samplingvoltage on a resistor (current detection resistor) coupled to the otherend of the primary winding. The first voltage sampling circuit 1062 cansample the modulated first voltage by sampling the voltage cross twoends of the primary winding.

Moreover, in an embodiment of the present disclosure, as illustrated inFIG. 12, the first voltage sampling circuit 1062 includes a peak voltagesampling and holding unit, a cross-zero sampling unit, a leakage unitand an AD sampling unit. The peak voltage sampling and holding unit isconfigured to sample and hold a peak voltage of the modulated firstvoltage. The cross-zero sampling unit is configured to sample a zerocrossing point of the modulated first voltage. The leakage unit isconfigured to perform a leakage on the peak voltage sampling and holdingunit at the zero crossing point. The AD sampling unit is configured tosample the peak voltage in the peak voltage sampling and holding unit soas to obtain the voltage sampling value via the control unit.

By providing with the peak voltage sampling and holding unit, thecross-zero sampling unit, the leakage unit and the AD sampling unit inthe first voltage sampling circuit 1062, the modulated first voltage maybe sampled accurately, and it can be guaranteed that the voltagesampling value corresponds to the peak value of each cycle of the secondalternating current and keeps synchronous with the peak voltage of thefirst voltage, i.e., the phase and variation trend of magnitude of thevoltage sampling value are consistent with those of peak voltage of thefirst voltage respectively.

According to an embodiment of the present disclosure, as illustrated inFIG. 13, the power adapter 1 further includes a second voltage samplingcircuit 114. The second voltage sampling circuit 114 is configured tosample the first voltage with the first ripple waveform. The secondvoltage sampling circuit 114 is coupled to the control unit 107. Whenthe voltage value sampled by the second voltage sampling circuit 114 isgreater than a first predetermined voltage value, the control unit 107controls the switch unit 102 to switch on for a predetermined timeperiod, for performing a discharge on the surge voltage, spike voltagein the first voltage with the first ripple waveform.

As illustrated in FIG. 13, the second voltage sampling circuit 114 canbe coupled to the first output end and the second output end of thefirst rectifier 101, so as to sample the first voltage with the firstripple waveform. The control unit 107 performs a determination on thevoltage value sampled by the second voltage sampling circuit 114. Whenthe voltage value sampled by the second voltage sampling circuit 114 isgreater than the first predetermined voltage value, it indicates thatthe power adapter 1 is suffering the lightning interference and a surgevoltage occurs, and thus it needs to drain off the surge voltage forensuring the safety and reliability of charging. The control unit 107controls the switch unit 102 to switch on for a certain time period, toform a leakage path, such that the surge voltage caused by the lightningis drained off, thus avoiding the interference of the lightning when thepower adapter charges the terminal, and effectively improving the safetyand reliability of the charging of the terminal. The first predeterminedvoltage value may be determined according to actual situations.

In an embodiment of the present disclosure, during a process that thepower adapter charges the battery in the terminal, the control unit 107is further configured to control the switch unit 102 to switch off whenthe voltage sampling value is greater than a second predeterminedvoltage value. Namely, the control unit 107 further performs adetermination on the voltage sampling value. When the voltage samplingvalue is greater than the second predetermined voltage value, itindicates that the voltage outputted by the power adapter 1 is too high.At this time, the control unit 107 controls the power adapter to stopcharging the terminal by controlling the switch unit 102 to switch off.In other words, the control unit 107 realizes the over-voltageprotection of the power adapter by controlling the switch unit 102 toswitch off, thus ensuring the safety of charging.

Certainly, in an embodiment of the present disclosure, the controllerobtains the voltage sampling value by performing a bidirectionalcommunication with the control unit, and controls the charging controlswitch to switch off when the voltage sampling value is greater than thesecond predetermined voltage value. Namely, the charging control switchis controlled to switch off at the terminal side, so as to stop thecharging process, such that the safety of charging can be ensured.

Further, the control unit 107 is further configured to control theswitch unit 102 to switch off when the current sampling value is greaterthan a predetermined current value. In other words, the control unit 107further performs a determination on the current sampling value. When thecurrent sampling value is greater than the predetermined current value,it indicates that the current outputted by the power adapter 1 is toohigh. At this time, the control unit 107 controls the power adapter tostop charging the terminal by controlling the switch unit 102 to switchoff. In other words, the control unit 107 realizes the over-currentprotection of the power adapter by controlling the switch unit 102 toswitch off, thus ensuring the safety of charging.

Similarly, the controller obtains the current sampling value byperforming the bidirectional communication with the control unit, andcontrols to switch off the charging control switch when the currentsampling value is greater than the predetermined current value. In otherwords, the charging control switch is controlled to be switched off atthe terminal side, so as to stop the charging process of the battery,thus ensuring the safety of charging.

The second predetermined voltage value and the predetermined currentvalue may be set or written into a storage of the control unit (forexample, the MCU of the power adapter) according to actual situations.

In embodiments of the present disclosure, the terminal may be a mobileterminal, such as a mobile phone, a mobile power supply such as a powerbank, a multimedia player, a notebook PC, a wearable device or the like.

With the charging system according to embodiments of the presentdisclosure, the power adapter is controlled to output the secondalternating current, and the second alternating current outputted by thepower adapter is directly applied to the battery of the terminal, thusrealizing second charging to the battery directly by the voltage/currentwith the alternating current waveform and realizing a closed-loopcontrol to an output of the power adapter by sampling at the primarywinding so as to make the second alternating current meet the chargingrequirement. A magnitude of the voltage/current with the alternatingcurrent waveform changes periodically, and for each cycle, the peakvoltage of the positive half is greater than the absolute value of thevalley voltage of the negative half. Thus, in contrast to theconventional constant voltage and constant current, a lithiumprecipitation of the lithium battery may be reduced, the service life ofthe battery may be improved, and a probability and intensity of arcdischarge of a contact of a charging interface may be reduced, theservice life of the charging interface may be prolonged, and it isbeneficial to reduce polarization effect of the battery, improvecharging speed, and decrease heat emitted by the battery, thus ensuringa reliability and safety of the terminal during the charging. Moreover,since the power adapter outputs the voltage with the alternating currentwaveform, it is unnecessary to provide an electrolytic condenser in thepower adapter, which not only realizes simplification andminiaturization of the power adapter, but also decreases cost greatly.

Embodiments of the present disclosure further provide a power adapter.The power adapter includes: a first rectifier, a switch unit, atransformer, a compositing unit, a first charging interface, a samplingunit and a control unit. The first rectifier is configured to rectify afirst alternating current and output a first voltage with a first ripplewaveform. The switch unit is configured to modulate the first voltageaccording to a control signal and output a modulated first voltage. Thetransformer is configured to output a plurality of voltages with ripplewaveforms according to the modulated first voltage. The compositing unitis configured to composite the plurality of voltages to output a secondalternating current, in which, for each cycle of the second alternatingcurrent, a peak voltage of a positive half is greater than an absolutevalue of a valley voltage of a negative half. The first charginginterface is coupled to an output end of the compositing unit, andconfigured to apply the second alternating current to a battery in aterminal via a second charging interface of the terminal when the firstcharging interface is coupled to the second charging interface, in whichthe second charging interface is coupled to the battery. The samplingunit is configured to sample voltage and/or current at a primary windingof the transformer to obtain a voltage sampling value and/or a currentsampling value. The control unit is coupled to the sampling unit and theswitch unit respectively, and configured to output the control signal tothe switch unit, and to adjust a duty ratio of the control signalaccording to the current sampling value and/or the voltage samplingvalue, such that the second alternating current meets a chargingrequirement of the terminal.

With the power adapter according to embodiments of the presentdisclosure, the second alternating current is outputted via the firstcharging interface, and the second alternating current is directlyapplied to the battery of the terminal via the second charging interfaceof the terminal, thus realizing second charging to the battery directlyby the voltage/current with the alternating current waveform andrealizing a closed-loop control to an output of the power adapter bysampling at the primary winding so as to make the second alternatingcurrent meet the charging requirement. A magnitude of thevoltage/current with the alternating current waveform changesperiodically, and for each cycle, the peak voltage of the positive halfis greater than the absolute value of the valley voltage of the negativehalf. Thus, in contrast to the conventional constant voltage andconstant current, a magnitude of the ripple output voltage/currentchanges periodically, such that a lithium precipitation of the lithiumbattery may be reduced, the service life of the battery may be improved,and a probability and intensity of arc discharge of a contact of acharging interface may be reduced, the service life of the charginginterface may be prolonged, and it is beneficial to reduce polarizationeffect of the battery, improve charging speed, and decrease heat emittedby the battery, thus ensuring a reliability and safety of the terminalduring the charging. Moreover, since the voltage with the alternatingcurrent waveform is output, it is unnecessary to provide an electrolyticcondenser, which not only realizes simplification and miniaturization ofthe power adapter, but also decreases cost greatly.

FIG. 16 is a flow chart of a charging method according to embodiments ofthe present disclosure. As illustrated in FIG. 16, the charging methodincludes the followings.

At block S1, when a power adapter is coupled to a terminal, a firstrectification is performed on alternating current inputted into thepower adapter to output a first voltage with a first ripple waveform.

In other words, a first rectifier in the power adapter rectifies theinputted alternating current (i.e., the mains supply, such asalternating current of 220V, 50 Hz or 60 Hz) and outputs the firstvoltage (for example, 100 Hz or 120 Hz) with the first ripple waveform,such as a voltage with a steamed bun waveform.

At block S2, the first voltage with the first ripple waveform ismodulated by a switch unit, and is converted by a transformer to obtaina plurality of voltages with ripple waveforms.

The switch unit may be formed of a MOS transistor. A PWM control isperformed on the MOS transistor to perform a chopping modulation on thevoltage with the steamed bun waveform. And then, the modulated firstvoltage is coupled to a secondary side by the transformer, such that thesecondary winding outputs the plurality of voltages with ripplewaveforms.

In an embodiment of the present disclosure, a high-frequency transformeris used for conversion, such that the size of the transformer is small,thus realizing miniaturization of the power adapter with high-power.

At block S3, the plurality of voltages are composited to output a secondalternating current. For each cycle of the second alternating current, apeak voltage of a positive half is greater than an absolute value of avalley voltage of a negative half. A voltage waveform of the secondalternating current is illustrated as FIG. 5.

In embodiments of the present disclosure, the transformer includes theprimary winding, a first secondary winding and a second secondarywinding. The transformer outputs a second voltage with a second ripplewaveform via the first secondary winding according to the modulatedfirst voltage and outputs a third voltage with a third ripple waveformvia the second secondary winding according to the modulated firstvoltage.

The second voltage and the third voltage are composited by thecompositing unit to output the second alternating current.

The second alternating current is applied to the battery of the terminalvia the second charging interface, so as to realize charging of thebattery of the terminal.

At block S4, voltage and/or current at a primary winding of thetransformer is sampled to obtain a voltage sampling value and/or acurrent sampling value.

At block S5, a duty ratio of a control signal for controlling the switchunit is adjusted according to the voltage sampling value and/or thecurrent sampling value, such that the second alternating current meets acharging requirement when the power adapter is coupled to the terminal.

In an embodiment, the second alternating current meeting the chargingrequirement means that, at least a peak voltage and a peak current ofthe second alternating current meet the charging voltage and chargingcurrent when the battery is charged. In other words, the control unit107 is configured to adjust the duty ratio of the control signal (suchas a PWM signal) according to voltage and/or current outputted by thepower adapter 1 and obtained by sampling at the primary side, so as toadjust the output of the compositing unit 104 in real time and realize aclosed-loop adjusting control, such that the second alternating currentmeets the charging requirement of the terminal 2, thus ensuring thestable and safe charging of the battery. In detail, a waveform of acharging voltage outputted to a battery is illustrated in FIG. 5, inwhich the waveform of the charging voltage is adjusted according to theduty ratio of the PWM signal.

Therefore, in embodiments of the present disclosure, by controlling theswitch unit 102, a PWM chopping modulation is directly performed on thefirst voltage with the first ripple waveform i.e. the steamed bunwaveform after a full-bridge rectification, and then a modulated voltageis sent to the high-frequency transformer and is coupled from theprimary side to the secondary side via the high-frequency transformer,and is subject to a waveform composition or splicing of the compositingunit to output the second alternating current with the alternatingwaveform. The second alternating current is applied to the batterydirectly so as to realize second charging to the battery. The voltageamplitude of the second alternating current may be adjusted according tothe duty ratio of the PWM signal, such that the output of the poweradapter may meet the charging requirement of the battery. It can be seenfrom that, the power adapter according to embodiments of the presentdisclosure, without providing electrolytic condensers at the primaryside and the secondary side, may directly charge the battery via thevoltage with the alternating current waveform, such that a size of thepower adapter may be reduced, thus realizing miniaturization of thepower adapter, and decreasing cost greatly.

According to an embodiment of the present disclosure, a frequency of thecontrol signal is adjusted according to the voltage sampling valueand/or the current sampling value. That is, the output of the PWM signalto the switch unit is controlled to maintain for a continuous timeperiod, and then stop for a predetermined time period and then restart.In this way, the voltage applied to the battery is intermittent, thusrealizing the intermittent charging of the battery, which avoids asafety hazard caused by heating phenomenon occurring when the battery ischarged continuously and improves the reliability and safety of thecharging to the battery. The control signal outputted to the switch unitis illustrated in FIG. 6.

Further, the above charging method includes: performing a communicationwith the terminal via the first charging interface to obtain statusinformation of the terminal, and adjusting the duty ratio of the controlsignal according to the status information of the terminal, the voltagesampling value and/or current sampling value.

In other words, when the second charging interface is coupled to thefirst charging interface, the power adapter and the terminal may sendcommunication query instructions to each other, and a communicationconnection can be established between the power adapter and the terminalafter corresponding reply instructions are received, such that the poweradapter can obtain the status information of the terminal, negotiateswith the terminal about the charging mode and the charging parameter(such as the charging current, the charging voltage) and controls thecharging process.

According to an embodiment of the present disclosure, a fourth voltagewith a fourth ripple waveform can be generated by a conversion of thetransformer, and the fourth voltage with the fourth ripple waveform canbe detected to generate a voltage detecting value, and the duty ratio ofthe control signal can be adjusted according to the voltage detectingvalue.

In detail, the transformer can be provided with an auxiliary winding.The auxiliary winding can generate the fourth voltage with the fourthripple waveform according to the modulated first voltage. The outputvoltage of the power adapter can be reflected by detecting the fourthvoltage with the fourth ripple waveform, and the duty ratio of thecontrol signal can be adjusted according to the voltage detecting value,such that the output of the power adapter meets the charging requirementof the battery.

In an embodiment of the present disclosure, sampling the voltage at theprimary winding of the transformer to obtain the voltage sampling valueincluding: sampling and holding a peak voltage of the modulated firstvoltage, and sampling a zero crossing point of the modulated firstvoltage; performing a leakage on a peak voltage sampling and holdingunit configured for sampling and holding the peak voltage at the zerocrossing point; and sampling the peak voltage in the peak voltagesampling and holding unit so as to obtain the voltage sampling value. Inthis way, an accurate sampling can be realized on the peak voltage ofthe modulated first voltage, and it can be guaranteed that the voltagesampling value keeps synchronous with the peak voltage of the firstvoltage, i.e., the phase and variation trend of magnitude of the voltagesampling value are consistent with those of the peak voltage of thefirst voltage respectively.

Further, in an embodiment of the present disclosure, the above chargingmethod includes: sampling the first voltage with the first ripplewaveform, and controlling the switch unit to switch on for apredetermined time period for performing a discharge on surge voltageand spike voltage in the first voltage with the first ripple waveformwhen a sampled voltage value is greater than a first predeterminedvoltage value.

The first voltage with the first ripple waveform is sampled so as todetermine the sampled voltage value. When the sampled voltage value isgreater than the first predetermined voltage value, it indicates thatthe power adapter is suffering the lightning interference and a surgevoltage occurs, and thus it needs to drain off the surge voltage forensuring the safety and reliability of charging. It is required tocontrol the switch unit to switch on for a certain time period, to forma leakage path, such that the surge voltage caused by the lightning isdrained off, thus avoiding the interference of the lightning when thepower adapter charges the terminal, and effectively improving the safetyand reliability of the charging of the terminal. The first predeterminedvoltage value may be determined according to actual situations.

According an embodiment of the present disclosure, a communication withthe terminal is performed via the first charging interface to determinethe charging mode. When the charging mode is determined as the secondcharging mode, the charging current and/or charging voltagecorresponding to the second charging mode can be obtained according tothe status information of the terminal, so as to adjust the duty ratioof the control signal according to the charging current and/or chargingvoltage corresponding to the second charging mode. The charging modeincludes the second charging mode and the first charging mode.

In other words, when the current charging mode is determined as thesecond charging mode, the charging current and/or charging voltagecorresponding to the second charging mode can be obtained according tothe status information of the terminal, such as the voltage, electricquantity, temperature of the battery, running parameters of the terminaland power consumption information of applications running on theterminal or the like. And the duty ratio of the control signal isadjusted according to the obtained charging current and/or chargingvoltage, such that the output of the power adapter meets the chargingrequirement, thus realizing the second charging of the terminal.

The status information of the terminal includes the temperature of thebattery. When the temperature of the battery is greater than a firstpredetermined temperature threshold, or the temperature of the batteryis less than a second predetermined temperature threshold, if thecurrent charging mode is the second charging mode, the second chargingmode is switched to the first charging mode. The first predeterminedtemperature threshold is greater than the second predeterminedtemperature threshold. In other words, when the temperature of thebattery is too low (for example, corresponding to less than the secondpredetermined temperature threshold) or too high (for example,corresponding to greater than the first predetermined temperaturethreshold), it is unsuitable to perform the second charging, such thatit needs to switch from the second charging mode to the first chargingmode. In embodiments of the present disclosure, the first predeterminedtemperature threshold and the second predetermined temperature thresholdcan be set according to actual situations.

In an embodiment of the present disclosure, the switch unit iscontrolled to switch off when the temperature of the battery is greaterthan a predetermined high temperature protection threshold. Namely, whenthe temperature of the battery exceeds the high temperature protectionthreshold, it needs to apply a high temperature protection strategy tocontrol the switch unit to switch off, such that the power adapter stopscharging the battery, thus realizing the high protection of the batteryand improving the safety of charging. The high temperature protectionthreshold may be different from or the same to the first temperaturethreshold. In an embodiment, the high temperature protection thresholdis greater than the first temperature threshold.

In another embodiment of the present disclosure, the terminal furtherobtains the temperature of the battery, and controls to stop chargingthe battery (for example by controlling a charging control switch toswitch off at the terminal side) when the temperature of the battery isgreater than the predetermined high temperature protection threshold, soas to stop the charging process of the battery and to ensure the safetyof charging.

Moreover, in an embodiment of the present disclosure, the chargingmethod further includes: obtaining a temperature of the first charginginterface, and controlling the switch unit to switch off when thetemperature of the first charging interface is greater than apredetermined protection temperature. In other words, when thetemperature of the charging interface exceeds a certain temperature, thecontrol unit needs to apply the high temperature protection strategy tocontrol the switch unit to switch off, such that the power adapter stopscharging the battery, thus realizing the high protection of the batteryand improving the safety of charging.

Certainly, in another embodiment of the present disclosure, the terminalobtains the temperature of the first charging interface by performingthe bidirectional communication with the power adapter via the secondcharging interface. When the temperature of the first charging interfaceis greater than the predetermined protection temperature, the terminalcontrols the charging control switch to switch off, i.e., the chargingcontrol switch can be switched off at the terminal side, so as to stopthe charging process of the battery, thus ensuring the safety ofcharging.

During a process that the power adapter charges the terminal, the switchunit is controlled to switch off when the voltage sampling value isgreater than a second predetermined voltage value. Namely, adetermination is performed on the voltage sampling value during theprocess that the power adapter charges the terminal. When the voltagesampling value is greater than the second predetermined voltage value,it indicates that the voltage outputted by the power adapter is toohigh. At this time, the power adapter is controlled to stop charging theterminal by controlling the switch unit to switch off. In other words,the over-voltage protection of the power adapter is realized bycontrolling the switch unit to switch off, thus ensuring the safety ofcharging.

Certainly, in an embodiment of the present disclosure, the terminalobtains the voltage sampling value by performing a bidirectionalcommunication with the power adapter via the second charging interface,and controls to stop charging the battery when the voltage samplingvalue is greater than the second predetermined voltage value. Namely,the charging control switch is controlled to switch off at the terminalside, so as to stop the charging process, such that the safety ofcharging can be ensured.

In an embodiment of the present disclosure, during the process that thepower adapter charges the terminal, the switch unit is controlled toswitch off when the current sampling value is greater than apredetermined current value. In other words, during the process that thepower adapter charges the terminal, a determination is performed on thecurrent sampling value. When the current sampling value is greater thanthe predetermined current value, it indicates that the current outputtedby the power adapter is too high. At this time, the power adapter iscontrolled to stop charging the terminal by controlling the switch unitto switch off. In other words, the over-current protection of the poweradapter is realized by controlling the switch unit to switch off, thusensuring the safety of charging.

Similarly, the terminal obtains the current sampling value by performingthe bidirectional communication with the power adapter via the secondcharging interface, and controls to stop charging the battery when thecurrent sampling value is greater than the predetermined current value.In other words, the charging control switch is controlled to be switchedoff at the terminal side, such that the charging process of the batteryis stopped, thus ensuring the safety of charging.

The second predetermined voltage value and the predetermined currentvalue may be set according to actual situations.

In embodiments of the present disclosure, the status information of theterminal includes the electric quantity of the battery, the temperatureof the battery, the voltage/current of the battery of the terminal,interface information of the terminal and information on a pathimpedance of the terminal.

In detail, the power adapter can be coupled to the terminal via auniversal serial bus (USB) interface. The USB interface may be a generalUSB interface, or a micro USB interface. A data wire in the USBinterface is configured as the data wire in the first charginginterface, and configured for the bidirectional communication betweenthe power adapter and the terminal. The data wire may be D+ and/or D−wire in the USB interface. The bidirectional communication may refer toan information interaction performed between the power adapter and theterminal.

The power adapter performs the bidirectional communication with theterminal via the data wire in the USB interface, so as to determine tocharge the terminal in the second charging mode.

As an embodiment, when the power adapter performs the bidirectionalcommunication with the terminal via the first charging interface so asto determine to charge the terminal in the second charging mode, thepower adapter sends a first instruction to the terminal. The firstinstruction is configured to query the terminal whether to start thesecond charging mode. The power adapter receives a first replyinstruction from the terminal. The first reply instruction is configuredto indicate that the terminal agrees to start the second charging mode.

As an embodiment, before the power adapter sends the first instructionto the terminal, the power adapter charges the terminal in the firstcharging mode. When the power adapter determines that a chargingduration of the first charging mode is greater than a predeterminedthreshold, the power adapter sends the first instruction to theterminal.

In an embodiment, when the power adapter determines that a chargingduration of the first charging mode is greater than a predeterminedthreshold, the power adapter may determine that the terminal hasidentified it as a power adapter, such that the second charging querycommunication may start.

As an embodiment, the power adapter is controlled to adjust a chargingcurrent to a charging current corresponding to the second charging modeby controlling the switch unit. Before the power adapter charges theterminal with the charging current corresponding to the second chargingmode, a bidirectional communication is performed with the terminal viathe first charging interface to determine a charging voltagecorresponding to the second charging mode, and the power adapter iscontrolled to adjust a charging voltage to the charging voltagecorresponding to the second charging mode.

As an embodiment, performing the bidirectional communication with theterminal via the first charging interface to determine the chargingvoltage corresponding to the second charging mode includes: sending bythe power adapter a second instruction to the terminal, receiving by thepower adapter a second reply instruction sent from the terminal, anddetermining by the power adapter the charging voltage corresponding tothe second charging mode according to the second reply instruction. Thesecond instruction is configured to query whether a current outputvoltage of the power adapter is suitable for being used as the chargingvoltage corresponding to the second charging mode. The second replyinstruction is configured to indicate that the current output voltage ofthe power adapter is suitable, high or low.

As an embodiment, before controlling the power adapter to adjust thecharging current to the charging current corresponding to the secondcharging mode, the charging current corresponding to the second chargingmode is determined by performing the bidirectional communication withthe terminal via the first charging interface.

As an embodiment, determining the charging current corresponding to thesecond charging mode by performing the bidirectional communication withthe terminal via the first charging interface includes: sending by thepower adapter a third instruction to the terminal, receiving by thepower adapter a third reply instruction sent from the terminal anddetermining by the power adapter the charging current corresponding tothe second charging mode according to the third reply instruction. Thethird instruction is configured to query a maximum charging currentsupported by the terminal. The third reply instruction is configured toindicate the maximum charging current supported by the terminal.

The power adapter may determine the above maximum charging current asthe charging current corresponding to the second charging mode, or mayset the charging current as a charging current less than the maximumcharging current.

As an embodiment, during the process that the power adapter charges theterminal in the second charging mode, the bidirectional communication isperformed with the terminal via the first charging interface, so as tocontinuously adjust a charging current outputted to the battery from thepower adapter by controlling the switch unit.

The power adapter may query the status information of the terminalcontinuously, so as to adjust the charging current continuously, forexample, query the voltage of the battery of the terminal, the electricquantity of the battery, etc.

As an embodiment, performing the bidirectional communication with theterminal via the first charging interface to continuously adjust thecharging current outputted to the battery from the power adapter bycontrolling the switch unit includes: sending by the power adapter afourth instruction to the terminal, receiving by the power adapter afourth reply instruction sent by the terminal, and adjusting thecharging current by controlling the switch unit according to the currentvoltage of the battery. The fourth instruction is configured to query acurrent voltage of the battery in the terminal. The fourth replyinstruction is configured to indicate the current voltage of the batteryin the terminal.

As an embodiment, adjusting the charging current by controlling theswitch unit according to the current voltage of the battery includes:adjusting the charging current outputted to the battery from the poweradapter to a charging current value corresponding to the current voltageof the battery by controlling the switch unit according to the currentvoltage of the battery and a predetermined correspondence betweenbattery voltage values and charging current values.

In detail, the power adapter may store the correspondence betweenbattery voltage values and charging current values in advance.

As an embodiment, during the process that the power adapter charges theterminal in the second charging mode, it is determined whether there isa poor contact between the first charging interface and the secondcharging interface by performing the bidirectional communication withthe terminal via the first charging interface. When it is determinedthat there is the poor contact between the first charging interface andthe second charging interface, the power adapter is controlled to quitthe second charging mode.

As an embodiment, before determining whether there is the poor contactbetween the first charging interface and the second charging interface,the power adapter receives information indicating a path impedance ofthe terminal from the terminal. The power adapter sends a fourthinstruction to the terminal. The fourth instruction is configured toquery a current voltage of the battery in the terminal. The poweradapter receives a fourth reply instruction sent by the terminal. Thefourth reply instruction is configured to indicate the current voltageof the battery in the terminal. The power adapter determines a pathimpedance from the power adapter to the battery according to an outputvoltage of the power adapter and the current voltage of the battery anddetermines whether there is the poor contact between the first charginginterface and the second charging interface according to the pathimpedance from the power adapter to the battery, the path impedance ofthe terminal, and a path impedance of a charging wire between the poweradapter and the terminal.

As an embodiment, before the power adapter is controlled to quit thesecond charging mode, a fifth instruction is sent to the terminal. Thefifth instruction is configured to indicate that there is the poorcontact between the first charging interface and the second charginginterface.

After sending the fifth instruction, the power adapter may quit thesecond charging mode or reset.

The second charging process according to embodiments of the presentdisclosure is described from the perspective of the power adapter, andthen the second charging process according to embodiments of the presentdisclosure will be described from the perspective of the terminal in thefollowing.

In embodiments of the present disclosure, the terminal supports thefirst charging mode and the second charging mode. The charging currentof the second charging mode is greater than that of the first chargingmode. The terminal performs the bidirectional communication with thepower adapter via the second charging interface such that the poweradapter determines to charge the terminal in the second charging mode.The power adapter outputs according to a charging current correspondingto the second charging mode, for charging the battery in the terminal.

As an embodiment, performing by the terminal the bidirectionalcommunication with the power adapter via the second charging interfacesuch that the power adapter determines to charge the terminal in thesecond charging mode includes: receiving by the terminal the firstinstruction sent by the power adapter, in which the first instruction isconfigured to query the terminal whether to start the second chargingmode; sending by the terminal a first reply instruction to the poweradapter. The first reply instruction is configured to indicate that theterminal agrees to start the second charging mode.

As an embodiment, before the terminal receives the first instructionsent by the power adapter, the battery in the terminal is charged by thepower adapter in the first charging mode. When the power adapterdetermines that a charging duration of the first charging mode isgreater than a predetermined threshold, the terminal receives the firstinstruction sent by the power adapter.

As an embodiment, before the power adapter outputs according to thecharging current corresponding to the second charging mode for chargingthe battery in the terminal, the terminal performs the bidirectionalcommunication with the power adapter via the second charging interface,such that the power adapter determines the charging voltagecorresponding to the second charging mode.

As an embodiment, performing by the terminal the bidirectionalcommunication with the power adapter via the second charging interfacesuch that the power adapter determines the charging voltagecorresponding to the second charging mode includes: receiving by theterminal a second instruction sent by the power adapter, and sending bythe terminal a second reply instruction to the power adapter. The secondinstruction is configured to query whether a current output voltage ofthe power adapter is suitable for being used as the charging voltagecorresponding to the second charging mode. The second reply instructionis configured to indicate that the current output voltage of the poweradapter is suitable, high or low.

As an embodiment, before the terminal receives the charging currentcorresponding to the second charging mode from the power adapter forcharging the battery in the terminal, the terminal performs thebidirectional communication with the power adapter via the secondcharging interface, such that the power adapter determines the chargingcurrent corresponding to the second charging mode.

Performing by the terminal the bidirectional communication with thepower adapter via the second charging interface such that the poweradapter determines the charging current corresponding to the secondcharging mode includes: receiving by the terminal a third instructionsent by the power adapter, in which the third instruction is configuredto query a maximum charging current supported by the terminal; sendingby the terminal a third reply instruction to the power adapter, in whichthe third reply instruction is configured to indicate the maximumcharging current supported by the terminal, such that the power adapterdetermines the charging current corresponding to the second chargingmode according to the maximum charging current.

As an embodiment, during a process that the power adapter charges theterminal in the second charging mode, the terminal performs thebidirectional communication with the power adapter via the secondcharging interface, such that the power adapter continuously adjusts acharging current outputted to the battery.

Performing by the terminal the bidirectional communication with thepower adapter via the second charging interface such that the poweradapter continuously adjusts a charging current outputted to the batteryincludes: receiving by the terminal a fourth instruction sent by thepower adapter, in which the fourth instruction is configured to query acurrent voltage of the battery in the terminal; sending by the terminala fourth reply instruction to the power adapter, in which the fourthreply instruction is configured to indicate the current voltage of thebattery in the terminal, such that the power adapter continuouslyadjusts the charging current outputted to the battery according to thecurrent voltage of the battery.

As an embodiment, during the process that the power adapter charges theterminal in the second charging mode, the terminal performs thebidirectional communication with the control unit, such that the poweradapter determines whether there is a poor contact between the firstcharging interface and the second charging interface.

Performing by the terminal the bidirectional communication with thepower adapter, such that the power adapter determines whether there isthe poor contact between the first charging interface and the secondcharging interface includes: receiving by the terminal a fourthinstruction sent by the power adapter, in which the fourth instructionis configured to query a current voltage of the battery in the terminal;sending by the terminal a fourth reply instruction to the power adapter,in which the fourth reply instruction is configured to indicate thecurrent voltage of the battery in the terminal, such that the poweradapter determines whether there is the poor contact between the firstcharging interface and the second charging interface according to anoutput voltage of the power adapter and the current voltage of thebattery.

As an embodiment, the terminal receives a fifth instruction sent by thepower adapter. The fifth instruction is configured to indicate thatthere is the poor contact between the first charging interface and thesecond charging interface.

In order to initiate and adopt the second charging mode, the poweradapter may perform a second charging communication procedure with theterminal, for example, by one or more handshakes, so as to realize thesecond charging of battery. Referring to FIG. 7, the second chargingcommunication procedure according to embodiments of the presentdisclosure and respective stages in the second charging process will bedescribed in detail. Communication actions or operations illustrated inFIG. 7 are merely exemplary. Other operations or various modificationsof respective operations in FIG. 7 can be implemented in embodiments ofthe present disclosure. In addition, respective stages in FIG. 7 may beexecuted in an order different from that illustrated in FIG. 7, and itis unnecessary to execute all the operations illustrated in FIG. 7. Acurve in FIG. 7 represents a variation trend of a peak value or a meanvalue of the charging current, rather than a curve of actual chargingcurrent.

In conclusion, with the charging method according to embodiments of thepresent disclosure, the power adapter is controlled to output the secondalternating current meeting the charging requirement, and the secondalternating current outputted by the power adapter is directly appliedto the battery of the terminal, thus realizing second charging to thebattery directly by the voltage/current with the alternating currentwaveform and realizing a closed-loop control to an output of the poweradapter by sampling at the primary winding so as to make the secondalternating current meet the charging requirement. A magnitude of thevoltage/current with the alternating current waveform changesperiodically, and for each cycle, the peak voltage of the positive halfis greater than the absolute value of the valley voltage of the negativehalf. Thus, in contrast to the conventional constant voltage andconstant current, a lithium precipitation of the lithium battery may bereduced, the service life of the battery may be improved, and aprobability and intensity of arc discharge of a contact of a charginginterface may be reduced, the service life of the charging interface maybe prolonged, and it is beneficial to reduce polarization effect of thebattery, improve charging speed, and decrease heat emitted by thebattery, thus ensuring a reliability and safety of the terminal duringthe charging. Moreover, since the power adapter outputs the voltage withthe alternating current waveform, it is unnecessary to provide anelectrolytic condenser in the power adapter, which not only realizessimplification and miniaturization of the power adapter, but alsodecreases cost greatly.

As illustrated in FIG. 17, a charging device 1000 according toembodiments of the present disclosure includes a charging receivingterminal 1001, a voltage adjusting circuit 1002 and a central controlmodule 1003.

The charging receiving terminal 1001 is configured to receivealternating current from a mains supply. An input end of the voltageadjusting circuit 1002 is coupled to the charging receiving terminal1001. An output end of the voltage adjusting circuit 1002 is coupled toa battery (such as a battery 202 in a terminal). The voltage adjustingcircuit 1002 is configured to adjust the alternating current from themains supply to output a second alternating current, and to directlyapply the second alternating current to the battery for charging thebattery, in which, for each cycle of the second alternating current, apeak voltage of a positive half is greater than an absolute value of avalley voltage of a negative half. The central control module 1003 isconfigured to control the voltage adjusting circuit 1002 to adjustvoltage and/or current of the second alternating current, so as torespond the charging requirement of the battery.

According to an embodiment of the present disclosure, a peak voltage ofthe second alternating current is smaller than a peak voltage of thealternating current from the mains supply, and a cycle of the secondalternating current is greater than a cycle of the alternating currentfrom the mains supply.

According to an embodiment of the present disclosure, as illustrated inFIG. 18, the charging device 1000 may be arranged in the power adapter1.

According to an embodiment of the present disclosure, as illustrated inFIG. 19, the charging device 1000 may also be arranged in the terminal2.

With the charging device according to embodiments of the presentdisclosure, by adjusting the alternating current from the mains supply,the second alternating current which meets the charging requirement ofthe battery can be outputted and directly applied to the battery forperforming a second charging on the battery. In contrast to theconventional constant voltage and constant current, a lithiumprecipitation of the lithium battery may be reduced, the service life ofthe battery may be improved, and a probability and intensity of arcdischarge of a contact of a charging interface may be reduced, theservice life of the charging interface may be prolonged, and it isbeneficial to reduce polarization effect of the battery, improvecharging speed, and decrease heat emitted by the battery, thus ensuringa reliability and safety of the terminal during the charging.

Moreover, embodiments of the present disclosure also provide a chargingmethod. The charging method includes: receiving alternating current froma mains supply; adjusting the alternating current from the mains supplyto output a second alternating current; applying the second alternatingcurrent directly to a battery to charge the battery, in which, for eachcycle of the second alternating current, a peak voltage of a positivehalf is greater than an absolute value of a valley voltage of a negativehalf; adjusting voltage and/or current of the second alternating currentin response to the charging requirement of the battery.

According to an embodiment of the present disclosure, a peak voltage ofthe second alternating current is smaller than a peak voltage of thealternating current from the mains supply, and a cycle of the secondalternating current is greater than a cycle of the alternating currentfrom the mains supply.

With the charging method according to embodiments of the presentdisclosure, by adjusting the alternating current from the mains supply,the second alternating current which meets the charging requirement ofthe battery can be outputted and directly applied to the battery forperforming a second charging on the battery. In contrast to theconventional constant voltage and constant current, a lithiumprecipitation of the lithium battery may be reduced, the service life ofthe battery may be improved, and a probability and intensity of arcdischarge of a contact of a charging interface may be reduced, theservice life of the charging interface may be prolonged, and it isbeneficial to reduce polarization effect of the battery, improvecharging speed, and decrease heat emitted by the battery, thus ensuringa reliability and safety of the terminal during the charging.

In at least one embodiment of the present disclosure, part or allstructure (hardware and software) of the adapter can be integrated intothe terminal. Integrated structure of the adapter and the terminal canbe called as the charging system of the present disclosure, or called asa terminal.

In the specification of the present disclosure, it is to be understoodthat terms such as “central,” “longitudinal,” “lateral,” “length,”“width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,”“right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,”“clockwise,” “counterclockwise,” “axial,” “radial,” and “circumference”refer to the orientations and location relations which are theorientations and location relations illustrated in the drawings, and fordescribing the present disclosure and for describing in simple, andwhich are not intended to indicate or imply that the device or theelements are disposed to locate at the specific directions or arestructured and performed in the specific directions, which could not tobe understood to the limitation of the present disclosure.

In addition, terms such as “first” and “second” are used herein forpurposes of description and are not intended to indicate or implyrelative importance or significance or to imply the number of indicatedtechnical features. Thus, the feature defined with “first” and “second”may comprise one or more of this feature. In the description of thepresent disclosure, “a plurality of” means two or more than two, unlessspecified otherwise.

In the present disclosure, unless specified or limited otherwise, theterms “mounted,” “connected,” “coupled,” “fixed” and the like are usedbroadly, and may be, for example, fixed connections, detachableconnections, or integral connections; may also be mechanical orelectrical connections; may also be direct connections or indirectconnections via intervening structures; may also be inner communicationsof two elements, which can be understood by those skilled in the artaccording to specific situations.

In the present disclosure, unless specified or limited otherwise, astructure in which a first feature is “on” or “below” a second featuremay include an embodiment in which the first feature is in directcontact with the second feature, and may also include an embodiment inwhich the first feature and the second feature are not in direct contactwith each other, but are contacted via an additional feature formedtherebetween. Furthermore, a first feature “on,” “above,” or “on top of”a second feature may include an embodiment in which the first feature isright or obliquely “on,” “above,” or “on top of” the second feature, orjust means that the first feature is at a height higher than that of thesecond feature; while a first feature “below,” “under,” or “on bottomof” a second feature may include an embodiment in which the firstfeature is right or obliquely “below,” “under,” or “on bottom of” thesecond feature, or just means that the first feature is at a heightlower than that of the second feature.

Reference throughout this specification to “an embodiment,” “someembodiments,” “one embodiment”, “another example,” “an example,” “aspecific example,” or “some examples,” means that a particular feature,structure, material, or characteristic described in connection with theembodiment or example is included in at least one embodiment or exampleof the present disclosure. Thus, the appearances of the phrases such as“in some embodiments,” “in one embodiment”, “in an embodiment”, “inanother example,” “in an example,” “in a specific example,” or “in someexamples,” in various places throughout this specification are notnecessarily referring to the same embodiment or example of the presentdisclosure. Furthermore, the particular features, structures, materials,or characteristics may be combined in any suitable manner in one or moreembodiments or examples.

Those skilled in the art may be aware that, in combination with theexamples described in the embodiments disclosed in this specification,units and algorithm steps can be implemented by electronic hardware, ora combination of computer software and electronic hardware. In order toclearly illustrate interchangeability of the hardware and software,components and steps of each example are already described in thedescription according to the function commonalities. Whether thefunctions are executed by hardware or software depends on particularapplications and design constraint conditions of the technicalsolutions. Persons skilled in the art may use different methods toimplement the described functions for each particular application, butit should not be considered that the implementation goes beyond thescope of the present disclosure.

Those skilled in the art may be aware that, with respect to the workingprocess of the system, the device and the unit, reference is made to thepart of description of the method embodiment for simple and convenience,which are described herein.

In embodiments of the present disclosure, it should be understood that,the disclosed system, device and method may be implemented in other way.For example, embodiments of the described device are merely exemplary.The partition of units is merely a logical function partitioning. Theremay be other partitioning ways in practice. For example, several unitsor components may be integrated into another system, or some featuresmay be ignored or not implemented. Further, the coupling between eachother or directly coupling or communication connection may beimplemented via some interfaces. The indirect coupling or communicationconnection may be implemented in an electrical, mechanical or othermanner.

In embodiments of the present disclosure, it should be understood that,the units illustrated as separate components can be or not be separatedphysically, and components described as units can be or not be physicalunits, i.e., can be located at one place, or can be distributed ontomultiple network units. It is possible to select some or all of theunits according to actual needs, for realizing the objective ofembodiments of the present disclosure.

In addition, each functional unit in the present disclosure may beintegrated in one progressing module, or each functional unit exists asan independent unit, or two or more functional units may be integratedin one module.

If the integrated module is embodied in software and sold or used as anindependent product, it can be stored in the computer readable storagemedium. Based on this, the technical solution of the present disclosureor a part making a contribution to the related art or a part of thetechnical solution may be embodied in a manner of software product. Thecomputer software produce is stored in a storage medium, including someinstructions for causing one computer device (such as a personal PC, aserver, or a network device etc.) to execute all or some of steps of themethod according to embodiments of the present disclosure. Theabove-mentioned storage medium may be a medium able to store programcodes, such as, USB flash disk, mobile hard disk drive (mobile HDD),read-only memory (ROM), random-access memory (RAM), a magnetic tape, afloppy disc, an optical data storage device, and the like.

Although explanatory embodiments have been illustrated and described, itwould be appreciated by those skilled in the art that the aboveembodiments cannot be construed to limit the present disclosure, andchanges, alternatives, and modifications can be made in the embodimentswithout departing from spirit, principles and scope of the presentdisclosure.

What is claimed is:
 1. A power adapter, comprising: a first rectifier,configured to rectify a first alternating current and output a firstvoltage with a first ripple waveform; a switch unit, configured tomodulate the first voltage according to a control signal and output amodulated first voltage; a transformer, configured to output a pluralityof voltages with ripple waveforms according to the modulated firstvoltage; a compositing unit, configured to composite the plurality ofvoltages to output a second alternating current, wherein, for each cycleof the second alternating current, a peak voltage of a positive half isgreater than an absolute value of a valley voltage of a negative half,and the second alternating current is configured to be introduced into aterminal to charge a battery in the terminal when the power adapter iscoupled to the terminal; a sampling unit, configured to sample voltageand/or current at a primary winding of the transformer to obtain avoltage sampling value and/or a current sampling value; a control unit,coupled to the sampling unit and the switch unit respectively, andconfigured to output the control signal to the switch unit, and toadjust a duty ratio of the control signal according to the currentsampling value and/or the voltage sampling value, such that the secondalternating current meets a charging requirement of the terminal whenthe power adapter is coupled to the terminal.
 2. The power adapteraccording to claim 1, wherein the transformer comprises the primarywinding, a first secondary winding and a second secondary winding, afirst end of the primary winding is coupled to a first output end of thefirst rectifier, a second end of the primary winding is coupled to theswitch unit, the first secondary winding and the second secondarywinding both are coupled to the compositing unit, and the transformer isconfigured to output a second voltage with a second ripple waveform viathe first secondary winding according to the modulated first voltage,and to output a third voltage with a third ripple waveform via thesecond secondary winding according to the modulated first voltage;wherein the compositing unit is configured to composite the secondvoltage and the third voltage to output the second alternating current.3. The power adapter according to claim 1, wherein the control unit isfurther configured to adjust a frequency of the control signal accordingto the voltage sampling value and/or the current sampling value.
 4. Thepower adapter according to claim 1, wherein the control unit is furtherconfigured to communicate with the terminal so as to obtain statusinformation of the terminal when the power adapter is coupled to theterminal; wherein the control unit is further configured to adjust theduty ratio of the control signal according to the voltage sampling valueand/or the current sampling value and the status information of theterminal.
 5. The power adapter according to claim 1, further comprising:a driving unit, coupled between the switch unit and the control unit,and configured to drive the switch unit to switch on or off according tothe control signal; and an isolation unit, coupled between the drivingunit and the control unit.
 6. The power adapter according to claim 5,further comprising: an auxiliary winding, configured to generate afourth voltage with a fourth ripple waveform according to the modulatedfirst voltage; and a power supply unit, coupled to the auxiliarywinding, and configured to convert the fourth voltage and output a firstdirect current, so as to supply power to the driving unit and/or thecontrol unit respectively.
 7. The power adapter according to claim 6,further comprising: a first voltage detecting unit, coupled to theauxiliary winding and the control unit respectively, and configured todetect the fourth voltage to generate a voltage detecting value, whereinthe control unit is further configured to adjust the duty ratio of thecontrol signal according to the voltage detecting value.
 8. The poweradapter according to claim 1, wherein a working frequency of thetransformer ranges from 50 KHz to 2 MHz.
 9. The power adapter accordingto claim 1, wherein the sampling unit comprises: a first currentsampling circuit, configured to sample the current at the primarywinding so as to obtain the current sampling value; and a first voltagesampling circuit, configured to sample the voltage at the primarywinding so as to obtain the voltage sampling value.
 10. The poweradapter according to claim 9, wherein the first voltage sampling circuitcomprises: a peak voltage sampling and holding unit, configured tosample and hold a peak voltage of the modulated first voltage; across-zero sampling unit, configured to sample a zero crossing point ofthe modulated first voltage; a leakage unit, configured to perform aleakage on the peak voltage sampling and holding unit at the zerocrossing point; and an AD sampling unit, configured to sample the peakvoltage in the peak voltage sampling and holding unit so as to obtainthe voltage sampling value.
 11. The power adapter according to claim 1,further comprising: a second voltage sampling circuit, configured tosample the first voltage, and coupled to the control unit, wherein thecontrol unit is configured to control the switch unit to switch on for afirst predetermined time period for discharging when a voltage valuesampled by the second voltage sampling circuit is greater than a firstpredetermined voltage value.
 12. The power adapter according to claim 1,wherein the power adapter comprises a first charging interface, thefirst charging interface comprises: a power wire, configured to chargethe battery; and a data wire, configured to communicate with theterminal when the power adapter is coupled to the terminal via the firstcharging interface; wherein the control unit is configured tocommunicate with the terminal via the first charging interface todetermine a charging mode, in which the charging mode comprises a secondcharging mode and a first charging mode, and the second charging mode isdifferent from the first charging mode.
 13. The power adapter accordingto claim 12, further comprising: a rectifying and filtering unit,configured to rectify and filter one of the plurality of voltages andoutput a second direct current, and a controllable switch, configured tocontrol an operation of the rectifying and filtering unit; wherein, thecontrol unit is further configured to, when determining the chargingmode as the first charging mode, control the rectifying and filteringunit to work by controlling the controllable switch and control thecompositing unit to stop working, such that the rectifying and filteringunit outputs the second direct current to charge the battery when thepower adapter is coupled to the terminal; when determining the chargingmode as the second charging mode, control the rectifying and filteringunit to stop working by controlling the controllable switch and controlthe compositing unit to work, such that the second alternating currentis applied to the battery.
 14. The power adapter according to claim 12,wherein the control unit s further configured to obtain a chargingcurrent and/or a charging voltage corresponding to the second chargingmode according to status information of the terminal when the poweradapter is coupled to the terminal, and to adjust the duty ratio of thecontrol signal according to the charging current and/or the chargingvoltage corresponding to the second charging mode, when determining thecharging mode as the second charging mode.
 15. The power adapteraccording to claim 14, wherein the status information of the terminalcomprises a temperature of the battery, wherein when the temperature ofthe battery is greater than a first predetermined temperature thresholdor the temperature of the battery is less than a second predeterminedtemperature threshold, the second charging mode is switched to the firstcharging mode when a current charging mode is the second charging mode,in which the first predetermined temperature threshold is greater thanthe second predetermined temperature threshold; wherein the control unitis further configured to control the switch unit to switch off when thetemperature of the battery is greater than a predetermined temperatureprotection threshold during the charging process.
 16. The power adapteraccording to claim 1, wherein the control unit is further configured to:control the switch unit to switch off when the voltage sampling value isgreater than a second predetermined voltage value; or control the switchunit to switch off when the current sampling value is greater than apredetermined current value; or obtain a temperature of a first charginginterface of the power adapter via which the power adapter is coupled tothe terminal, and to control the switch unit to switch off when thetemperature of the first charging interface is greater than apredetermined protection temperature.
 17. The power adapter according toclaim 12, wherein when performing bidirectional communication with theterminal via the data wire of the first charging interface to determineto charge the terminal in the second charging mode, the control unit isconfigured to send a first instruction to the terminal, in which thefirst instruction is configured to query the terminal whether to startthe second charging mode; and the control unit is configured to receivea first reply instruction from the terminal, in which the first replyinstruction is configured to indicate that the terminal agrees to startthe second charging mode.
 18. The power adapter according to claim 17,wherein, the control unit is configured to send the first instruction tothe terminal when determining that a charging duration of the firstcharging mode is greater than a predetermined threshold.
 19. The poweradapter according to claim 17, wherein the control unit is furtherconfigured to control the power adapter to adjust a charging current toa charging current corresponding to the second charging mode bycontrolling the switch unit, and before the power adapter charges theterminal with the charging current corresponding to the second chargingmode, the control unit is configured to perform bidirectionalcommunication with the terminal via the data wire of the first charginginterface to determine a charging voltage corresponding to the secondcharging mode, and to control the power adapter to adjust a chargingvoltage to the charging voltage corresponding to the second chargingmode.
 20. The power adapter according to claim 19, wherein whenperforming the bidirectional communication with the terminal via thedata wire of the first charging interface to determine the chargingvoltage corresponding to the second charging mode, the control unit isconfigured to send a second instruction to the terminal, in which thesecond instruction is configured to query whether a current outputvoltage of the power adapter is suitable for being used as the chargingvoltage corresponding to the second charging mode; the control unit isconfigured to receive a second reply instruction sent from the terminal,in which the second reply instruction is configured to indicate that thecurrent output voltage of the power adapter is suitable, high or low;and the control unit is configured to determine the charging voltagecorresponding to the second charging mode according to the second replyinstruction.
 21. The power adapter according to claim 19, wherein,before controlling the power adapter to adjust the charging current tothe charging current corresponding to the second charging mode, thecontrol unit is further configured to perform bidirectionalcommunication with the terminal via the data wire of the first charginginterface to determine the charging current corresponding to the secondcharging mode; wherein, when performing the bidirectional communicationwith the terminal via the data wire of the first charging interface todetermines the charging current corresponding to the second chargingmode, the control unit is configured to send a third instruction to theterminal, in which the third terminal is configured to query a maximumcharging current supported by the terminal; the control unit isconfigured to receive a third reply instruction sent from the terminal,in which the third reply instruction is configured to indicate themaximum charging current supported by the terminal; and the control unitis configured to determine the charging current corresponding to thesecond charging mode according to the third reply instruction.
 22. Thepower adapter according to claim 17, wherein the control unit is furtherconfigured to, during charging the terminal in the second charging modeby the power adapter, perform bidirectional communication with theterminal via the data wire of the first charging interface, so as tocontinuously adjust a charging current outputted to the battery from thepower adapter by controlling the switch unit; wherein, when performingthe bidirectional communication with the terminal via the data wire ofthe first charging interface to continuously adjust the charging currentoutputted to the battery from the power adapter by controlling theswitch unit, the control unit is configured to send a fourth instructionto the terminal, in which the fourth instruction is configured to querya current voltage of the battery in the terminal; the control unit isconfigured to receive a fourth reply instruction sent by the terminal,in which the fourth reply instruction is configured to indicate thecurrent voltage of the battery in the terminal; and the control unit isconfigured to adjust the charging current by controlling the switch unitaccording to the current voltage of the battery.
 23. The power adapteraccording to claim 22, wherein the control unit is configured to adjustthe charging current outputted to the battery from the power adapter toa charging current value corresponding to the current voltage of thebattery by controlling the switch unit according to the current voltageof the battery and a predetermined correspondence between batteryvoltage values and charging current values.
 24. The power adapteraccording to claim 21, wherein the control unit is further configuredto, during charging the terminal in the second charging mode by thepower adapter, determine whether there is a poor contact between thefirst charging interface and the second charging interface by performingthe bidirectional communication with the terminal via the data wire ofthe first charging interface, wherein, when determining that there isthe poor contact between the first charging interface and the secondcharging interface, the control unit is configured to control the poweradapter to quit the second charging mode.
 25. The power adapteraccording to claim 23, wherein, before determining whether there is apoor contact between the first charging interface and the secondcharging interface, the control unit is further configured to receiveinformation indicating a path impedance of the terminal from theterminal, wherein the control unit is configured to send a fourthinstruction to the terminal, in which the fourth instruction isconfigured to query a current voltage of the battery in the terminal;the control unit is configured to receive a fourth reply instructionsent by the terminal, in which the fourth reply instruction isconfigured to indicate the current voltage of the battery in theterminal; the control unit is configured to determine a path impedancefrom the power adapter to the battery according to an output voltage ofthe power adapter and the current voltage of the battery; and thecontrol unit is configured to determine whether there is the poorcontact between the first charging interface and the second charginginterface according to the path impedance from the power adapter to thebattery, the path impedance of the terminal, and a path impedance of acharging wire between the power adapter and the terminal.
 26. The poweradapter according to claim 25, wherein, before the power adapter quitsthe second charging mode, the control unit is further configured to senda fifth instruction to the terminal, in which the fifth instruction isconfigured to indicate that there is the poor contact between the firstcharging interface and the second charging interface.
 27. A chargingsystem, comprising: a battery; a first rectifier, configured to rectifya first alternating current and output a first voltage with a firstripple waveform; a switch unit, configured to modulate the first voltageaccording to a control signal and output a modulated first voltage; atransformer, configured to output a plurality of voltages with ripplewaveforms according to the modulated first voltage; a compositing unit,configured to composite the plurality of voltages to output a secondalternating current, wherein, for each cycle of the second alternatingcurrent, a peak voltage of a positive half is greater than an absolutevalue of a valley voltage of a negative half; a sampling unit,configured to sample voltage and/or current at a primary winding of thetransformer to obtain a voltage sampling value and/or a current samplingvalue; and a control unit, coupled to the sampling unit and the switchunit respectively, and configured to output the control signal to theswitch unit, to adjust a duty ratio of the control signal according tothe current sampling value and/or the voltage sampling value, such thatthe second alternating current meets a charging requirement of thebattery.
 28. The charging system according to claim 27, furthercomprising a terminal, wherein the battery is a component of theterminal.
 29. A charging method, comprising: performing a rectificationon a first alternating current to output a first voltage with a firstripple waveform; modulating the first voltage by controlling a switchunit, and outputting a plurality of voltages with ripple waveforms by aconversion of a transformer; compositing the plurality of voltages tooutput a second alternating current, wherein, for each cycle of thesecond alternating current, a peak voltage of a positive half is greaterthan an absolute value of a valley voltage of a negative half; applyingthe second alternating current to a battery; sampling voltage and/orcurrent at a primary winding of the transformer to obtain a voltagesampling value and/or a current sampling value; and adjusting a dutyratio of a control signal for controlling the switch unit according tothe voltage sampling value and/or the current sampling value, such thatthe second alternating voltage meets a charging requirement of thebattery.